The Kaii-Yōkai Denshō Database (怪異・妖怪伝承データベース) is a database of yōkai and mystery stories which have been collected from Japanese folklore. The database is published by International Research Center for Japanese Studies. The prototype was created on March 19, 2002, and the first live version was released on June 20, 2002. the project supervisor is Kazuhiko Komatsu, a Japanese folklorist who is a professor of the study of yōkai.