Tradition: Chinese Mythology, Japanese Mythology
Alternative Names: 仙鼠, Celestial Rat, Immortal Mouse, Tensō, Hiso
Category: Rat
The Myth
Senso, meaning “Immortal Rat,” is an old name for the bat, whose appearance resembles that of a mouse with wings. In traditional Chinese lore, bats were sometimes believed to originate from mice that had lived for an exceptionally long time. The Chinese text Xuanzhong Ji states that a mouse becomes a bat after reaching one hundred years of age.
The bat was also associated with longevity and immortality. According to the Xian Jing, it was known as the Senso and would turn silver-white after a thousand years. Ge Hong’s Baopuzi likewise describes thousand-year-old bats becoming as white as snow and associates them with substances used in the search for immortality.
These beliefs also appeared in poetry. The Tang poet Bai Juyi described a thousand-year-old mouse transforming into a white bat and hiding in a dark cave to escape danger. Another poem, quoted in the Japanese Jikkinshō, tells of a mouse that gains wings through immortality but is soon eaten by a crow or kite. The story warns against envying another’s fortune, suggesting that apparent advancement may still lead to danger.
Sources
“Senno.” 新版TYZ 妖怪図鑑 (New TYZ Yokai Encyclopedia). https://tyz-yokai.blog.jp/archives/1078433271.html