Who We Are

Since its founding in 2015, MAST has brought together professionals with deep expertise and wide-ranging experience to deliver legal services of the highest standard.

MAST is a boutique law firm where partners handle every matter directly, from start to finish.

MAST's attorneys are graduates of Seoul National University, Korea University, Ewha Womans University, and Ivy League law schools in the United States. They bring experience as corporate executives, consultants, in-house counsel, and law firm attorneys.

Our partners combine a deep understanding of business and management with long experience and legal expertise, and they do the work themselves, in advisory matters as much as in litigation.

When our clients succeed, MAST succeeds.

The principle is simple, and we have kept to it. It is the foundation of the trust we have built from our founding to the present day. What a client wants is a firm that treats the client's matter as its own and works on it wholeheartedly. That is why MAST insists that the interests of the client and the firm run together. As legal professionals we put good faith and professional ethics first, and we take on only those advisory and litigation matters in which our interests are aligned with the client's.

Brand

A Steadfast Pillar of Support, A Driving Force for Growth.
MAST Law Firm

Before we settled on the name MAST, we spent a long time asking what our brand and our firm name should mean. In the end we thought of the great adventurers who set out in the 15th-century Age of Discovery in search of new seas and new continents, and of the sailing ships that went with them. What drew our attention was the role of the mast: the spar that held the ship steady, carried it through storms, and let it sail the open sea.

Companies and individuals alike sail the uncharted waters of business and of life. At every unexpected issue, complex dispute, and critical decision along that long voyage, MAST Law Firm stands with its clients as a steadfast pillar of support that holds against the heaviest storms, and as a partner that adds a driving force for growth to a voyage worth making.

We do not seek a relationship that ends with a single matter. We want to remain a partner our clients trust and believe in, and a friend who is there in moments of joy and of sorrow.

Our promise is clear. Our clients' success is MAST's success.

The Meaning Behind Our Logo

The MAST logo combines the firm's English name with a triangle that stands for a sail — a ship raising its sail and setting out across the open sea.

Client Testimonials

"A Legal Partner of the Highest Ability, One We Can Trust"

After founding Fresheasy and leading its fresh HMR/mealkit business, I was looking for a partner I could trust with our complex legal problems, and was introduced to MAST Law Firm and Managing Partner Junghwan Lee. As Fresheasy grew from a single small room, through round after round of rocket growth, into the No. 1 company in Korea's fresh HMR sector, MAST Law Firm supported us as solidly as family and was there for every moment of joy and of sorrow. Fresheasy raised hundreds of billions of KRW from a great many investors including VCs, PE funds, and large corporations, and had MAST Law Firm's solid support in every area: M&A of subsidiaries, corporate financing for the construction of plants, large-scale plant construction, asset sales, general commercial transactions, responses to labor office investigations and HR and labor matters, corporate disputes, and litigation. In particular, in the course of a Buy-out M&A deal worth hundreds of billions of KRW with Anchor Equity Partners and the Bolt-on M&As of Tasty9, Heodak, and Dr. Kitchen that followed, they drew on their rich M&A experience to give precise legal advice day and night, and cleanly resolved the complex legal problems arising in the PMI process. Unlike lawyers in general, they responded meticulously, as if the matter were their own, on the strength of an understanding that reaches the inner workings of startups and companies, and they helped our management make accurate decisions. That, above all, is what I value. MAST Law Firm, which has been with us from our founding to this day, is the finest law firm, full of sincerity and passion, providing the best legal service to fast-growing companies and startups.

"A True Companion with Dedication to the Client and Expertise"

Many startup CEOs ask me what criteria they should use in choosing a law firm. I always say dedication and expertise. Many startup CEOs then ask whether there is a firm that has both. Without the slightest hesitation, I say MAST Law Firm. I remember when the A-ha team first came to know MAST. The company was in very poor shape at the time. We met with a great many firms, but none of them so much as looked closely at us or listened carefully to what we had to say. They seemed to think there was no money in it. But Managing Partner Junghwan Lee of MAST was the only one who looked into our situation personally, from beginning to end. Truly, from first to last. Companies grow through repeated ups and downs. The A-ha team's journey was a continuous run of hardship and difficulty until we achieved our highest sales and profit in 2023 and grew into a service with more than 10 million MAU, but I remember vividly how he would smile and cheer us on, saying, "You can do this, CEO." That indescribable magnetism has carried on to this day, more than ten years later. It is genuinely difficult for a manager to find a firm with both a warm heart and a cool head, but through dedication to the client and expertise MAST has established itself as a true companion on the A-ha team's long journey. They put the client's interests first and are always thinking about our success. MAST keeps watch on the latest trends and, on the basis of an in-depth understanding of the business, provides clear guidelines and legal service that let the A-ha team focus wholly on the business. I am happy and reassured to have MAST — a firm I can share a drink with when things are hard, and throw my arms around and cheer with when things go well. MAST is a partner that has been, is, and will go on being woven seamlessly into the A-ha team's success story. I would like to express my gratitude to MAST for helping the A-ha team so unfailingly for so long.

"A Law Firm Like a Friend and Colleague You Can Trust and Lean On at the Critical Moment"

While responding to the serious disputes that arose in the course of running Heodak, I was introduced to MAST Law Firm and Attorney Junghwan Lee, cleanly resolved the major dispute issues, and was able to complete the M&A with Fresheasy. From then on, running the online HMR business, I received help with the changes in business content and structure that came up constantly, with various disputes and lawsuits, and with complex legal issues. MAST's strength is that it grasps each problem quickly and, drawing on a deep understanding of management and industry and on extensive experience, weighs the many variables so that we can make the best choice. Unlike lawyers in general, who answer passively and only what they are asked, they asked questions actively, listened to management's views, put the whole matter and its issues together as if fitting a puzzle, and worked toward the best solution — watching that process built a deep relationship of trust. MAST helped us build a preemptive crisis response system, which became the footing for Heodak's rapid growth. In business, the times a law firm is needed seem to be the most joyful moments and the moments of greatest crisis — that is, the most dramatic and important moments. I am grateful to have met a true colleague and friend who helps me judge rightly with a calm mind at the important moments and whom I can trust and lean on in a moment of crisis.

"A Law Firm with a Deep Understanding of Business Management, Expertise, and Long Experience — I Recommend Them Strongly 🙂"

After founding Breezm and taking investment from a variety of investors, we ended up with preferred shares issued on different terms and a great many investment agreements. Entering the United States and raising overseas investment in 2024 became an important milestone for the company's growth, and we received a great deal of advice on both. In particular, we were advised that before raising overseas investment it was important to do the legal work of unifying the investment agreements and the terms of the preferred shares and aligning the shareholders' rights. On the strong recommendation of our investors and of CEOs of Kakao Investment portfolio startups, we were introduced to MAST Law Firm and Attorney Junghwan Lee. Before founding Breezm I was an IB banker at a securities firm, handling M&A advisory and PE investment, so investment and M&A in the capital markets were familiar to me and I thought I was confident enough to review the contracts myself. But the various investment agreements and shareholders' agreements had accumulated on different terms, shaped by the fast-changing startup investment environment and the circumstances of each round. Making them advantageous and fair from the perspective of the company and the founder was work we did together with MAST Law Firm, which has rich experience and deep expertise. Working with MAST Law Firm and looking at their analysis of nearly twenty different sets of preferred share terms, the rights under the shareholders' agreements, and the rights and obligations of the company and its stakeholders, I realized that in focusing only on the company's growth I had been missing things that mattered legally. Drawing on the rich experience of MAST Law Firm and Attorney Junghwan Lee, they attended carefully even to the management issues that could arise in the course of future growth, and revised and consolidated almost every clause in order to resolve in advance the problems that could arise in an M&A and from the standpoint of the company's governance and management. They also provided, option by option, ways of responding to investors holding different positions, and explained matters directly in investor meetings, so that a great many meetings went smoothly. After working with MAST Law Firm in the course of preparing to raise overseas investment, we entered into a retainer in order to receive continuing legal advice. Having gained a partner a founder can genuinely trust, I can now focus with an easy mind on running and growing the company. Having worked with them, I understood why so many people recommended MAST so strongly. I strongly recommend MAST Law Firm and Attorney Junghwan Lee to startups and founders of every kind 🙂

"A Law Firm You Cannot Help but Recommend Once You Have Worked Together — MAST Law Firm"

While looking for a law firm to handle the legal advice on XYZ's Series A round, I was recommended MAST Law Firm and Managing Partner Junghwan Lee by a number of startup CEOs. As a venture partner at FuturePlay who has invested directly in a variety of startups, and as a founder who has started several startups myself, I know that the investment terms and the outcome of later rounds differ according to the ability of the firm advising on the round, so I chose carefully, weighing each firm's expertise and its willingness to take the lead. MAST Law Firm's strength is the initiative and the sense of responsibility with which it drives the work forward, identifying and advising on problems the client had not thought of. Unlike investment rounds, which tend to proceed on the investors' terms, we were able to lead the negotiation on the strength of Attorney Junghwan Lee's rich experience with investment rounds and M&A deals. Because he proposed an investment structure, terms, and negotiating ideas that both the investors and we could be satisfied with, we brought a complex negotiation — one in which a financial investor and a strategic investor invested together — to a smooth close with a satisfying result. With its rich experience and expertise, MAST Law Firm understands the position of startups and founders better than anyone, and I believe it is the best partner for resolving the complex legal problems that arise in running a company, from incorporation through to an M&A. I hope you will go on being a solid partner to many startups and founders.

"The Law Firm You Can Trust and Rely On Most on an Uncertain Business Path, a Solid Partner for Founders"

I was introduced to MAST during the hardest period of stagnation in the business after founding a fintech startup. The growth of our existing business model had been stalled for a long time, and various financial regulations made it difficult to move straight ahead with the business we had devised, so it was hard to find our bearings. In that process, Managing Partner Junghwan Lee of MAST thought through our business strategy with us and proposed solutions to the related legal risks. With the new service and business model born of that process, we were designated an Innovative Financial Service by the Financial Services Commission last year, which gave us the chance to grow once again. Not only their expertise and experience, but the fact that they thought it through with us more passionately than anyone, remains a memory I am grateful for to this day. We continue to receive a great deal of help through ongoing legal advice on the company's important matters — the launch of new services, the Series B and C rounds, the OpenUp M&A, and more. For fintech startups like ours, which innovate on the traditional financial industry with digital technology, I believe MAST will be a more solid partner than any other law firm, on the strength of its comprehensive experience and expertise across startups, IT, and finance.

"Distinctive Legal Service, Expertise We Can Trust, Sincerity Felt from the Heart."

My relationship with MAST Law Firm, Attorney Junghwan Lee, and Attorney Sarah Alm Han goes back to my time at Blank Corporation, and we continue to work together at Makestar. As CFO of Makestar, I work with MAST Law Firm on everything: raising investment and dealing with investors, expanding into the entertainment business and the various investments that came with it, launching new services and reviewing their terms of use, and responding to complex disputes and litigation. In receiving legal advice from large firms and boutique firms and from a great many lawyers, I was often frustrated by "it could be this way, or it could be that way" answers, by answers that were merely general rather than pointed when I asked about a specific case, and by answers that explained a difficult problem in an even more difficult way. MAST is made up of lawyers who combine a deep understanding of the startup business environment and industry with legal expertise. They advise the company's staff accurately and in terms that are easy to understand, and provide the optimal solution from the standpoint of solving the problem — a distinctive strength that the members of our company deeply trust. Personally, in the Series B round that came not long after I became CFO of Makestar, they quickly grasped the many legal issues piled up in the company and gave meticulous legal advice, presenting the best legal answer at every step from the negotiation of the investment agreement and the shareholders' agreement among a great many domestic and overseas investors through to closing. It was a great strength to me, and I was moved by the efforts of lawyers who understood the position of the founder and the company, thought it through with us, and solved the problems. MAST Law Firm resolves the company's complex and difficult legal issues with the finest legal service. They are a partner for shared growth that we can trust.

"A Pillar of Support for Startups and IT Founders, MAST Law Firm"

My first connection with MAST Law Firm came through legal advice on the strategic investment into the virtual asset exchange Bithumb. Through MAST's legal advice I was able to understand precisely the meaning of the clauses of the investment agreement and of the unfamiliar legal terms in the shareholders' agreement — redeemable convertible preferred shares, liquidation preference, share put rights and the like — and the effect they would have on later rounds. There were twists and turns in the course of the negotiation, but on MAST's advice we were able to close the round on good terms. Having worked with MAST, I was convinced that this is a firm to be trusted in both expertise and work ethic. Since then I have received help in everything needed for product development and the company's growth: advice on the running of the company, legal advice on the development and launch of the ZUZU service, review of the service's terms of use, and more. In the KODEBOX M&A with Dunamu as well, we received legal advice from MAST Law Firm and Attorney Junghwan Lee, negotiated and executed the agreement on terms favorable to the founders, and were able to bring the M&A deal to a successful close. MAST's ability, which comes through naturally from its experience advising a great many companies and startups on investment, M&A, review of new businesses, dispute resolution, and regulatory review, is, I believe, its greatest competitive strength — one other lawyers cannot easily match. In any field, meeting a capable firm and capable people is not easy. When other CEOs ask me to recommend a law firm, I recommend MAST and Managing Partner Junghwan Lee with confidence.

"A Partner for Shared Growth with Expertise, Initiative, and Sincerity"

While selecting a law firm to handle the Ridi–Laftel M&A, I was recommended MAST and Managing Partner Junghwan Lee. Having worked with a range of firms, large firms among them, on M&A, investment, and various legal issues, I came to see that the outcome of the work differs according to the firm in charge. The structuring of the Ridi–Laftel M&A in particular was not easy, so we held preliminary meetings with many firms and selected MAST, which proposed the optimal structure, as our legal counsel. Working with MAST through the M&A, I was struck by how they identified issues preemptively — the problems the client had not thought of, the issues left unresolved, and the effects both short- and long-term — and did their utmost to find the best solution. Since that first engagement at Ridi, legal advice for the startups I have been at has always been with MAST. In particular, they cleanly resolved the complex issues that arose in improving Gowid's governance, and I think highly of the fast and accurate advice they gave through the whole process of FINDA's Series C round — the fundraising, the negotiation, and the execution of the various agreements — in which a Korean financial holding company took part as an SI and an overseas VC as an FI. The MAST I have worked with is a law firm that does its utmost for the client's success on the basis of "expertise," "initiative," and "sincerity," and a partner that founders and startups can trust.

"A Law Firm That Proves Itself to the Client in Both Process and Result"

Since founding Rarajob, we went through two rounds of investment and an M&A deal together with MAST Law Firm, and were able to bring a startup's life cycle to a successful close. It was not my first time founding a startup or raising investment, but because I knew that a clause or a phrase that looks trivial can have a serious effect on the future of the company and the founder, I came to work with MAST Law Firm on the recommendation of CEOs around me. When reviewing an investment deal, MAST exercises strong leadership so that the founder can make the right decision with an eye to the follow-on investment, M&A, or IPO that may come later. Because MAST took those situations into account in advance, the follow-on investment and the M&A that came afterward were able to proceed smoothly. The M&A was with SaraminHR, a listed company. We went through a long negotiation from acquisition structure to acquisition terms, the execution of the final agreement, and closing, with a great many adjustments to the M&A terms along the way. Each time, MAST drew on its expertise and wide M&A experience to put forward counter-terms and help us find a point of compromise. For matters that were difficult for me to explain to the existing shareholders or to SaraminHR as the acquirer, they explained directly in meetings and took part in the negotiation, doing everything they could to support the successful completion of the deal. The night before the final negotiation with SaraminHR, I stayed up through the night at the firm with Managing Partner Junghwan Lee discussing our strategy on the key M&A issues and revising the agreement. I will not soon forget going up to the firm's roof together, breathing the dawn air, and talking about small things. To the CEOs looking for a law firm for founders and startups, I recommend MAST Law Firm with all my heart.

"The Best Legal Partner, Protecting Founders and Startups"

I was recommended MAST and Attorney Junghwan Lee in the course of raising our Series B round. It was a round with a great deal of volatility in the terms because market conditions had worsened, and the situation felt overwhelming — legal due diligence, unifying the terms of the investment agreements between the existing and the new investors, consolidating the shareholders' agreements. After several months of negotiation, they gave us a great deal of help in reaching a reasonable agreement that fairly reflected the needs of the company, the founder, and the investors. Although it was a new round, it was done alongside the consolidation of the investment agreements and the shareholders' agreements. The earlier agreements contained various toxic clauses whose meaning I had not understood when I signed, as well as unreasonable clauses I had signed knowingly but without a choice. Seeing them set out, in options from best case to worst case, how to change all of it was a great strength to me. When it was hard for me, not knowing the law well, to persuade the investors, they explained a great many questions directly in meetings with the investors and prepared written opinions as well. The investors, too, accepted MAST's opinions as reasonable, so we were able to revise most of the clauses in the existing investment agreements and shareholders' agreements that were unfair to the founder and the company, and to bring the new investors in on the same terms. I was sincerely grateful. Through long experience and know-how in the startup field they know exactly which issues arise at each stage of a company's growth, and they have deep experience with investment rounds and M&A. It was striking to watch them provide, scenario by scenario, proposals that reduced the terms unfavorable to the founder and the startup and the legal risk while still securing the investors' rights, and build a solution the investors could accept. Since the Series B round we have entered into a legal retainer and manage our legal risk with advice on the whole of running the company — overseas expansion, product exports, new businesses, legal disputes relating to the construction of a new plant, HR, and more. MAST Law Firm gives unstinting advice, with expertise, adeptness, preemptive response, and sincerity, in the direction that lets the company grow soundly. For a founder, it is a firm to be deeply grateful for and to rely on.

"The Best Partner a Corporate Legal Officer Cannot Help but Trust"

At a time when our legal organization had no in-house counsel, our relationship began with the revision of the company's all-important service terms and conditions. From there it grew to cover civil and criminal matters, fair trade, copyright, and M&A feasibility review, and then the work of consolidating a compliance organization to reduce risk before it arose — all of it done together with MAST Law Firm. MAST Law Firm and Attorney Junghwan Lee were supporters and partners as reliable as in-house colleagues who share the good times and the bad. Because we are an IT company, discussions about advice or a legal solution normally come with IT terminology and technical content attached. With other firms, communication was somewhat difficult and considerable resources went into preparing background material; with MAST, which has wide experience in IT as well as in new businesses and global issues, none of those resources were wasted in the process, and the work went smoothly and quickly. It was also striking that, thanks to the excellent lawyers MAST has, we were able to obtain the best results on global legal issues and global disputes in English- and Japanese-speaking jurisdictions as well. Whenever a fast-moving business or legal issue had to be reviewed, they were the best partners — thinking about the matter deeply and seriously, immediately and quickly, and working day and night to arrive at a solution. I have many memories of calling early in the morning and being answered in a voice that sounded as though they had worked through the night, which made me all the more grateful and all the more sorry. Beyond ordinary legal work, when we were planning and building our compliance framework, they gave us advice that was fitted to our organization, appropriate, and offered without reservation. It drew on collaboration and know-how that only MAST had built up steadily with startups, small and medium enterprises, mid-sized companies, large corporations, and companies that had risen to the rank of large corporations in a single stride through explosive growth. That advice, I am confident, was the hidden foundation that let our organization become systematic and stable in a short time. Whatever legal or compliance issue may arise, if you are able to work with MAST Law Firm, I can recommend with confidence that both the process and the result will be the best available.

"A Law Firm That Supports You Solidly from the Founder's Position, with Expertise, Passion, and Ease"

Startups make new attempts on the strength of their own business and technical expertise, but in making those attempts and in raising investment they run into difficulty for want of experience and because the situations are unfamiliar. RideFlux is a startup pioneering the mobility field on the basis of autonomous driving technology. After receiving our first investment from SOCAR and SOQRI, we devoted ourselves to technology development; then, in the course of raising a Series A round from VCs, I ran into a great deal of difficulty as CEO. MAST, whom we came to work with on the recommendation of SOQRI, an existing investor, is a partner that gives a clear explanation of a complicated situation and finds the solution as well, on the basis of expertise and a great deal of experience. Rather than stopping at fragmentary, one-sided advice, they thought through the larger picture in a structure suited to the company's situation, and found a point of agreement that suited both the company and the investors. Above all, I am sincerely grateful that they made it possible to consult with them with an easy mind, and that they responded with enthusiasm regardless of the hour. I hope many startups will be able to realize their dreams with MAST, which provides accurate legal advice for founders with expertise and with affection for startups.

"The Best Law Firm, Crying and Laughing with Its Clients and Growing Alongside Them"

MAST and Managing Partner Junghwan Lee have been with the life of the company called Accio from its incorporation through legal review for product launches, business agreements, and an M&A. When you set up a company, the shareholders' agreement among the co-founders matters a great deal. Everyone starts of one mind, but because unexpected things happen in the course of running a company, the importance of that agreement is much emphasized. I believe the relationship of trust among the co-founders greatly affects what goes into it. MAST did not hand us a boilerplate shareholders' agreement; they looked closely at the relationships among us, Accio's founders, and worked that well into the agreement. That was the beginning of a good relationship of trust with MAST. Trust grew deeper still while we worked on the M&A agreement between Kakao and Accio. The acquisition negotiation took more than six months and was a hard time. Through it we shared all sorts of feelings — laughing together, and sometimes them getting angrier on our behalf than we did — and we got through the hard time together and reached a good result. Drawing on the expertise of many M&As, they made great efforts on many fronts: not only reviewing and revising the agreement but advising on the negotiation as a whole and dealing with Kakao's people. They also understood well my relationship with Kakao, having already sold a company to Kakao once before, and ran the M&A deal so that this was properly reflected. Even now we receive MAST's legal advice on the whole of Accio's affairs — joint business agreements with our parent company, legal review for the launch of new services — and they will be with us on the journey ahead. I would like to recommend MAST to every IT founder and startup CEO in need of legal advice.

"The Best Law Firm for Startups"

For GymT, past its early stage and having to think about growth in earnest, MAST's legal advice was truly a great help. Going through the Series A round with a number of investors together with Managing Partner Junghwan Lee, we broke through many obstacles and were able to take investment on the good terms the founders wanted. They reviewed the whole range of corporate legal matters — the investment agreement, the shareholders' agreement, the articles of incorporation, stock options — very carefully and accurately, and in the investment negotiation they drew on rich experience to put forward a range of legal solutions that both the company and the investors could be satisfied with, so that we brought a difficult negotiation to a good close. With an attitude of working as one with the client, and with difficult legal issues explained accurately and in an easy-to-understand way in a relaxed atmosphere, decision-making as CEO became far easier. Please go on being a good partner to startups!

"MAST, a Companion to Startups"

In a startup, it is demanding enough just to focus on the core work of developing and improving the service, so it was hard to attend to legal matters as well. When a significant lawsuit arose in the course of running the company, I came to work with MAST on the recommendation of other CEOs. Seeing MAST's attorneys work passionately on the client's side in litigation with a serious bearing on the running of the company, resolving one issue after another and leading us to a good result, we came to build a deep relationship of trust with the firm. Since then MAST has resolved every legal issue arising in the running of the company — VC investment, various disputes, civil and criminal litigation, government relations, corporate legal work — always with a good result. This was a great help in Kim Tutoring becoming the No. 1 service in the private tutoring matching market, and I am sincerely grateful. MAST considers matters from the client's position without fail and genuinely cares for its startup clients. I recommend the firm to many founders.

"A Law Firm More at Ease and More Accurate Than Any Other"

During a legal dispute with an M&A advisor that arose in the course of the sale of Thebanchan, I was recommended Attorney Junghwan Lee and received valuable advice. Since then, having founded PurpleLabs and worked with MAST, I have received a great deal of help in a variety of areas: legal advice on the various issues arising across the running of the business, civil litigation and dispute response, raising investment and negotiating it, stock options, and more. Having worked with law firms of many kinds and met a great many lawyers, I liked that MAST was not a stiff, rigid firm; I felt very much at ease with them. That let me confide a wider range of concerns and receive accurate legal advice. I wish you well in establishing yourselves as a solid partner that grows with and supports every startup and founder!

Who We Are

MAST is a boutique law firm where partners handle every matter directly, from start to finish.

Brand