Aobōzu

Aobōzu is a kaii (strange phenomena) with blue skin, appearing in the form of a robed figure—often a Buddhist monk—in temple precincts and mountain roads after dark. Accounts frequently describe it as a one-eyed tall figure, and encounters are narrated in connection with a temple's founding history (engi), often involving a riddle posed to the traveller. Variants are recorded across northern Honshu and Hokkaido, suggesting continuity with blue-skinned and tall-figure legends found throughout mainland Japan.

In typical accounts, a traveller on a night mountain path or in the grounds of an abandoned temple suddenly encounters a towering blue-skinned monk blocking the way. The figure is said to pose riddles or questions, terrifying those who cannot answer, or to emit such an overwhelming presence that mere sight of it causes the witness to lose consciousness. The phenomenon shares themes with *tenjo-sagari* (ceiling-drop) and *daidōnyudō* (giant monk) legends; its non-human blue colouration is understood as an element that heightens its otherworldly character.

Aobōzu appears as a woodblock print in Toriyama Sekien's *Konjaku Gazu Zoku Hyakki* (1779), where it is depicted as a one-eyed robed figure. Hokkaido, colonised by Japanese settlers mainly from the early modern period onward, likely received Aobōzu narratives as imported variants from Honshu. Records appear in *Nihon Yōkai Daijiten* (2005) and the International Research Center for Japanese Studies' 'Kaii and Yōkai Folklore Database'.

Related phenomena include *aonyudō* (blue monk), *mikoshi-nyudō* (exceeding-height monk), and *daidōnyudō* (giant monk), with which it shares iconographic and thematic elements. Aobōzu appears in various Honshu regions; the Tōhoku region privileges *daidōnyudō* accounts; Kyushu has one-eyed monk variants. The Hokkaido tradition is understood as a northern transmission of these mainland narratives.