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My area of expertise is civil law, which governs property and family rights and obligations. In particular, I focus my research on legal systems related to contracts. Jurisprudence, which deals with rules between people, is often mistakenly thought to be the study of interpreting existing systems, but for me, research is nothing more than constantly questioning existing rules in order to build a more desirable society.

Currently, my main focus is on issues such as the "demand for transparency" in consumer contracts. When we sign a contract for a smartphone or register for an online service, we enter into a contract with a business. In this situation, we, as consumers, and the business are by no means in an equal relationship. Businesses possess an overwhelming amount of information about their products and present very long, predetermined contracts (terms and conditions), and in most cases, consumers have no choice but to agree to them. Laws such as the Consumer Contract Act have been established to rectify this structural disparity.

However, the current legal system is not perfect, and society is constantly changing. A particular problem is the lack of clarity in contract terms. For example, when signing up for a subscription service, consumers are required to scroll through very long and detailed terms and conditions. It is not realistic for consumers to read and understand all of this accurately. If these contract terms are unclear or ambiguous, consumers may mistakenly believe that they do not have the rights they are entitled to, or that they are obligated to bear obligations they are not entitled to.

In previous discussions of civil law, the ambiguity of contract clauses has been treated not as a matter of whether the contract is unfair or not, but rather as a matter of information disclosure during the contract-making process or a matter of contract interpretation. However, I believe this way of thinking should be re-examined. In consumer contracts, businesses should be strongly required to ensure transparency in contract clauses. If this transparency is not maintained, and the content is such that consumers are misled about the content of their rights and obligations, then this ambiguity could not only become a problem in the interpretation of the clauses, but could also become a problem of the unfairness of the clauses. This is the core of my current research, and in November 2025 I published a book summarizing this, "Consumer Contracts and Transparency" (Shinzan-sha).

A monograph on consumer contracts and the demand for transparency, published in 2025.

I believe that studying the law means confronting the reality of an unequal society and pursuing more desirable institutional designs to protect people's fair interests.

Comparative analysis with French law is an indispensable method in my research. This doesn't mean I consider French law superior to Japanese law. Rather, by analyzing the legal systems of other countries, we can sometimes find useful perspectives for solving the challenges we face. One of the greatest joys of my research lies precisely in discovering these "different perspectives."

The previously mentioned "Consumer Contracts and Transparency" was also examined based on perspectives derived from French law, but let's introduce some other systems. There is a problem called the "partial invalidity doctrine," which concerns how to determine the extent to which a contract becomes invalid. This is a very important issue: when a clause or part of a clause in a contract has a ground for invalidity, does that clause or part of the clause become invalid, or does the entire contract become invalid? In conventional discussions, it has been argued that the scope of invalidity should be determined by the intentions of the parties, specifically whether the parties wished for the remaining parts to remain in effect.

However, I have doubts about whether everything should truly be explained solely by the parties involved. The existence of grounds for invalidity means that there has already been a violation of legal norms (mandatory provisions). For example, although this has already been resolved by legislation in Japan, suppose there is a clause in a loan agreement that stipulates interest rates exceeding the legal limit. If the borrower were to claim that the clause was unfair, and the lender could simply say, "Then I wouldn't have entered into the contract. The entire contract is invalid, so please return the principal immediately," the borrower would be afraid to take the matter of unfair interest to court. In this case, the legal norms established by law would become meaningless, and their effectiveness could not be ensured.

Here, the concept of French law provided an important clue. In France, invalidation is positioned as a "sanction (legal measure) to restore legality." Here, "sanction" does not mean punitive, but rather a means to ensure the effectiveness of the law. Therefore, when determining the scope of invalidation, the underlying idea is that while the intentions of the parties are not completely ignored, the purpose of the legal norm should be given importance. The essence of invalidation is seen as maximizing the realization of the purpose of the legal norm and encouraging violations by invalidating only the unfair clauses.

Drawing on this perspective from French law, I proposed a new idea that the scope of invalidity should not be determined solely by considering the intentions of the parties, but rather by considering the purpose of the legal norm and ensuring its effectiveness. By analyzing foreign law, I was able to find a clue to a solution to a long-standing problem in Japan that had been stalled for many years. The results of this research were compiled in the book "The Multilayered Structure of Partial Invalidity Theory" (Nihon Hyoronsha), published in 2020.

A monograph on the theory of partial invalidity, published in 2020.

What brings me the most joy through my research is when I discover new perspectives and clues to solving the challenges of Japanese law through the analysis of laws from other countries. At that moment, it feels like finding a missing piece of a puzzle, and when I can see a path leading to a better system, I feel a great sense of fulfillment, as if the foundation of my research, "law exists for the people," is being satisfied.

High school students may be accustomed to solving problems with definite answers through their schoolwork. However, university studies, especially legal research, involve confronting questions without definitive answers. Law, the rules of society, requires critical thinking about whether they can keep pace with an ever-changing society and how they should be structured to build a more desirable society. This critical thinking is becoming increasingly important in today's rapidly evolving AI society. While it's true that we can easily obtain certain answers by asking AI, those answers are not always correct or appropriate. Discovering what the problems are in society today and considering how to apply existing legal systems or create new ones to solve them—this is the true value of university research and studying law.

The challenges of modern society are lurking even in our immediate surroundings. For example, there is an increasing number of cases where 18- and 19-year-olds, who lack social experience, enter into various contracts for online services and other services on their own. In reality, there are many cases where they become involved in unfair troubles related to these contracts. Should we treat young adults, who are vulnerable in terms of information and experience, the same way as other consumers? What kind of system should be in place to protect them? This is a major challenge that modern civil law is currently facing.

My research topic, "Transparency in Consumer Contracts," aims to eliminate unfair or misleading clauses hidden within consumer contracts we enter into. By deterring unfair contract clauses, I hope to reduce the risk of all consumers, including young people, getting involved in troubles and contribute to creating a fairer market order.

Individual presentations at the 83rd Annual Meeting of the Japan Association of Private Law