On January 17, 2022 Keiko Mitani, а prominent representative of Japan Palaeoslavistics, who contributed greatly to the development of the contemporary history of the Old Church Slavonic, Russian, Croatian and Old Bulgarian passed away. Keiko Mitani was born in 1957 in Tokyo. She received a bachelor’s degree in Russian Language and Russian Literature, from the Faculty of Letters, the University of Tokyo (1981) and an MA degree in the same subject from the Graduate School of Humanities, University of Tokyo (March 1983). Keiko Mitani continued her research work during her doctoral studies at the Graduate School of Humanities (April 1983 – March 1989). At that time she was able to study Croatian and Slavic literatures in the Balkan context at the Faculty of Philosophy, University of Zagreb (October 1986 – September 1988) under the supervision of Professor Stjepan Damjanović (of the Croatian Academy of Sciences and Arts). In 1990 she got the position of Research Associate at the University of Tokyo, Faculty of Letters (Russian Language and Literature), and later – Lecturer at the Department of Literature and Linguistics, University of Tsukuba (1993) where she was Assistant Professor (1997). Developing active research and teaching activities she became an Associate Professor at Kyoto University, Graduate School of Human and Environmental Studies (1999), and Professor (2005). In 2013 she was a Professor at the University of Tokyo, Graduate School of Humanities and Sociology (Department of Slavic Languages and Literatures). Her rese