“In the Imperial House Law, the crown prince is defined as follows: ‘The son of the Emperor who is the Imperial Heir is called kōtaishi.’ Therefore, although Prince Akishino has been declared the heir to the throne and given the title of kōshi, he is not the kōtaishi. This is why the name of the ceremony that was performed was different. The crown prince (kōtaishi) system was introduced to Japan from China around 700 A.D. Prior to that, there was no crown prince system in Japan. Therefore, Prince Shōtoku, who served as a regent of Empress Suiko during the Asuka period (538-710), is not referred to as ‘Crown Prince’, although he was the second son of Emperor Yomei.”

“The crown prince system itself began somewhere between the late Asuka period and the Nara period (710-794), or in the era of ancient Japan, but the focus of my research is on the medieval period that stretches from the mid-to-late Heian period (794-1185) to the Kamakura period (1185-1333). I’m trying to paint a clear picture of the position of crown prince from about 900 A.D. To 1300 A.D.”

“I am focusing on the behavior of crown princes during rituals to identify clues that reveal their attributes. The most important of these ceremonies are the rittaishi-no-rei, which proclaim who the crown prince shall be, and conversely, cases where crown princes were deposed, as well as genpuku, a coming-of-age ceremony, and gyokei, or official outings taken by crown princes. Take the gyokei, for example. The decoration of the vehicle carrying the crown prince and the arrangement of the processions ahead and behind him are all meticulously defined, and naturally there is some kind of meaning behind them. Therefore, I believe that comparing these ceremonies with those of the preceding and following eras will allow me to clarify the attributes of crown princes in medieval Japan."

“Another topic I am exploring is support personnel, that is, the officials who surrounded crown princes. Crown princes were supported by numerous people in administrative positions, such as the tōgū-no-fu and tōgū-gakushi, two types of educational officers. The tōgū-no-fu was the top official who served the crown prince, and was the person closest to him. His role was to provide guidance to the crown prince on matters such as the appropriate ways to behave according to each situation, but to date, scholars have paid little attention to these officials. I have already conducted a detailed study of tōgū-no-fu, which revealed that the activities of these officials and how they were appointed were greatly influenced by the political trends of the time. The roles and actions of the tōgū-no-fu and the tōgū-gakushi, who were the crown prince’s exclusive teachers in a variety of disciplines, are essentially stipulated in the Ritsuryō, or the legal system of the time. For this reason, detailed actions are believed to have changed with each era and depending on the personnel. One example of important historical documents I referred to when exploring these changes are the diaries and writings left by the people of this era.”

“I wrote my undergraduate thesis on the retired emperors’ official outings to Uji during the period of cloistered rule, when the emperors retained power even after descending the throne. At that time, Uji was politically important as the epicenter of the Regent Houses. After this, I advanced to graduate school where I wanted to choose a topic that had both social and academic significance, so I decided to focus on the attributes of crown princes. I conceived of this topic because I thought it was timely, due to the growing interest in the Imperial Household system in the wake of Emperor Akihito—now Emperor Emeritus—abdicating while he was still alive. With the Imperial Household system at such a critical juncture, I thought it would be useful for future discussions of the system if I could identify the attributes of crown princes. What’s more, as I read through articles on medieval history again, I realized that surprisingly little is known about crown princes in medieval Japan. I drew inspiration from the fact that this topic had not been dealt with much in the past, and I felt it would be a worthwhile pursuit.”

“When you actually look into the articles, you find there are very few studies that focus solely on the position of crown prince in medieval Japan. Although scholars in the past have studied the political significance of crown princes, none of them have narrowed down their focus on the behaviors and other attributes of crown princes. This is why my topic demonstrates originality, something that is required above all else in research. That being said, the lack of prior research means there are no clues from the literature or historical documents that would typically be presented in research papers. In fact, I have not been able to find any historical documents that directly describe the position that crown princes filled.”

“I think it is important to communicate with people who have different views from mine and who have knowledge that I don't have to gain some insights from the limited historical materials. This is because, in many cases, you can gain new insights by holding discussions with people like these. I try to participate as much as possible in on-campus seminars and academic conferences in the Kansai area to diversify my knowledge.”

“In each case, I visit the archives in person, read through the catalogs, and make educated guesses based on the titles. When I start reading the historical documents that I locate in this way, I am usually drawn in at once. Of course, not all of them are helpful, and indeed, there is only a small handful that I can actually use for my research. When you start reading these kinds of historical documents, you can end up getting carried away, so if you don't draw a line somewhere, you will be immersed in documents 24/7. This is how fascinating it is to encounter unknown historical documents, so self-management is vital. If I get sick and it interferes with my research, then it's not worth it.”

“In a field where there is no precedent for research, the work that you consistently put in will directly accumulate as research achievements. I believe this to be my greatest strength. My ideal at this point is to become a researcher whose research on crown princes leads to me being asked for my opinions on the imperial system as well.”