Kokan Shiren no Zen Shiso no Kenkyu (A Study of the Zen Thought of Kokan Shiren: Revival and Originality in Medieval Japanese Zen)

This book investigates the thought of Kokan Shiren 虎関師錬 (1278–1346), a Zen monk active in medieval Japan. Shiren belonged to the Shōichi School 聖一派, a branch of Zen Buddhism tracing its origins to Enni 円爾 (1202–1280), the teacher of Shiren’s teacher. The school played an important role in helping Zen take root in medieval Japan, especially in Kyoto. Shiren is widely known as the author of the Genkō Shakusho 元亨釈書, the first comprehensive history of Japanese Buddhism, and his poetry and prose written in literary Chinese have also attracted the attention of scholars as precursors to Gozan literature 五山文学, a form of Zen-influenced literature that flourished from the late Kamakura period through the Muromachi period.
 
Yet these achievements have tended to overshadow another important aspect of his legacy: his philosophical contributions. In particular, little sustained research has been devoted to clarifying Shiren’s own philosophical perspective on Zen. This absence of scholarship, however, does not diminish its significance. To examine Shiren’s thought is also to reconsider the development of the Shōichi School and to gain insight into the process by which Zen took root and evolved in Japan. Building on recent advances in research on the Shōichi School, this book seeks to contribute to the intellectual history of medieval Zen.
 
This study reveals the nature of the thought that Kokan Shiren developed during the late Kamakura and Nanbokuchō periods, roughly one hundred years after Zen teachings had begun to be transmitted to Japan on a substantial scale from China. At a time, when multiple understandings of Zen coexisted, Shiren sought to return to what he regarded as the original sources of Zen and Buddhist tradition. By reinterpreting texts and traditions that he considered closer to those origins, he constructed a distinctive and original system of Zen philosophy. This book characterizes that process as “revival and originality in medieval Japanese Zen.”
 
The greater part of the volume is devoted to careful philological investigation and close textual analysis of some of Shiren’s philosophical works. Part I, The Writings of Kokan Shiren, presents foundational and critical studies of those works of Shiren that are indispensable for the study of his thought: the Shōshūron 正修論 (“The Treatise on Correct Practice”), the Zen Kaiki 禅戒軌 (“Manual of Zen Precepts”), and the Butsugo Shinron 仏語心論 (“The Treatise on the ‘Heart of Buddha’s Words’ Chapter from the Laṅkāvatāra Sūtra 楞伽経”). Part II, The Zen Thought of Kokan Shiren, examines these texts from multiple perspectives, including discussions concerning proper and improper ways of understanding and teaching Zen, the relationship between practice and enlightenment, views on the status and interpretation of sūtras, and understandings of precepts in Zen. On this basis, the book further attempts to situate Shiren’s perspective on Zen philosophy within the history of Zen thought more broadly.
 
The volume also includes a transcription and complete annotated translation of the Shōshūron, the text in which Shiren’s Zen thought is expressed most concisely and systematically. In this respect, the book aims to provide a foundation for future research not only on medieval Zen and Japanese Buddhism but also across a wide range of fields concerned with Shiren’s writings and thought.
 
At the same time, by focusing on Kokan Shiren, this book also explores a broader question: how ideas imported from other countries are reinterpreted, take root, and develop into distinctive forms in new cultural settings. It is my hope that this study may speak to readers with a wide range of interests in Japanese history, Zen Buddhism, and intellectual history more generally.
 

(Written by SAKUMA Yūi, Assistant Professor, Graduate School of Humanities and Sociology / 2026)