Old Diaries of Japan Sakkaiki 7 (The Diary of Nakayama Sadachika)

The Historiographical Institute (HI) at the University of Tokyo serves as a cornerstone for Japanese historical studies, primarily dedicated to the meticulous compilation and publication of primary source materials from the pre-modern era. Within this institution, I am part of the department specialized in the research of diaries written by court nobles (kuge), contributing to the prestigious series Dainihon Kokiroku (Old Diaries of Japan). My primary responsibility in recent years has been the stewardship and compilation of the Sakkaiki.
 
The Sakkaiki is the personal diary of Nakayama Sadachika (1401–1459), a prominent court noble of the Muromachi period. Sadachika occupied the pivotal role of Buke Denso, a high-ranking official charged with facilitating communication between the Imperial Court and the Muromachi Shogunate. His tenure largely coincided with the rule of the sixth Shogun, Ashikaga Yoshinori, a period marked by complex political maneuvers. Consequently, his diary serves as an unparalleled record of the delicate negotiations between the court and the military government. Furthermore, as an authority on court rituals and precedents (yusoku kojitsu), Sadachika left behind exhaustive accounts of ceremonies. His observations are now considered indispensable for scholars analyzing the political climate, power dynamics, and ritual life of 15th-century Japan.
 
The surviving portions of the diary span nearly three decades, from 1418 (Oei 25), when Sadachika began his official career, to 1447 (Bun-an 4), shortly after his retirement. However, the transmission of the text was far from perfect; the original record has significant lacunae, and much of the overall work has been lost to time.
 
The project to compile Dainihon Kokiroku: Sakkaiki began in earnest in 1995. Over the course of nearly three decades, from 1999 to 2023, we published a total of eight volumes (seven main text volumes and one supplementary volume). The final installment, Volume 7, represents the culmination of this effort, featuring not only the diary text but also an extensive introduction (kaidai), a chronological biography, genealogical tables, a list of emendations, and a comprehensive index. As the third lead researcher on this project, I inherited a vast legacy of scholarship from my predecessors and personally oversaw the completion of the final three volumes.
 
The compilation process is an arduous journey of historical reconstruction. We must locate original manuscripts or high-quality transcriptions, decipher complex cursive script (kuzushiji), and establish a definitive text through rigorous philological analysis. Since few of Sadachika’s original holographs survive, we rely heavily on later copies. Because Sadachika’s expertise was so revered, many Edo-period scholars produced transcriptions or thematic excerpts of his work.
 
The true "thrill" of this work lies in the detective labor: comparing multiple manuscripts to identify the most authentic phrasing, or deducing the date of an anonymous fragment based on internal evidence. Often, we discover that a seemingly unrelated record is, in fact, a missing piece of the Sakkaiki. This process of restoring a fragmented past is made possible by the archives and research traditions accumulated at the Historiographical Institute since the Meiji era.
 
To ensure these records remain accessible to the modern global audience, the Dainihon Kokiroku series is being digitized. Our "Full-text Database of Old Diaries" currently provides searchable access to 43 major titles. I invite researchers and enthusiasts alike to explore this digital archive to uncover the rich tapestry of Japan’s historical memory.
 

(Written by ENDO Tamaki, Associate Professor, Historiographical Institute / 2026)