Tradition: Japanese Mythology
Alternative Names: 頼豪院, Raigō仙人 (Raigō Sennin)
Category: Rat
The Myth
Raigōin is a sorcerer and practitioner of black magic in Santō Kyōden’s historical fantasy novel Mukashigatari Inazuma Byōshi. Set during the Chōroku era (1457–1460), the story follows the intrigues of the Sasaki family, where powerful retainers plot to control the family inheritance. Raigōin is hired by the corrupt steward Fuwa Dōken to curse Tsukiwaka, the young heir to the family estate.
After Raigōin performs his rituals, Tsukiwaka falls gravely ill and suffers terrifying attacks by swarms of rats. The creatures first appear at night, while his attendants fall asleep, but eventually invade his room even during the day. They gnaw away his hair and scalp, leaving painful, poisonous sores. One night, the warrior Yamazaburō witnesses a gigantic rat, as large as a dog, attacking the boy. He strikes it with a small blade, whereupon the rat releases smoke and transforms into Raigōin. The sorcerer escapes by chanting spells, unleashing a violent wind, and spitting dozens of rats from his mouth to attack his pursuer. With the sorcerer wounded, Tsukiwaka begins to recover.
Raigōin later helps Dōken and his ally, Kuchide no Kata, frame Tsukiwaka and his mother, Ginnan no Mae, for using curses against the family. Their conspiracy leads to the mother and son being condemned, but they are rescued by loyal retainers. Eventually, Raigōin is captured and forced to confess his involvement in the plot, exposing the conspirators and bringing about their downfall. The character draws inspiration from the historical monk Raigō of Miidera, whose legend tells of his transformation after death into a swarm of rats. Stories about this monk often depict him becoming a giant rat or spewing rats from his mouth. Raigōin’s confrontation with Yamazaburō also echoes theatrical scenes in which the villainous Niki Danjō or Suganuma Kosuke reveals himself after taking the form of a rat.
Sources
“Raigouin.” 新版TYZ 妖怪図鑑 (New TYZ Yokai Encyclopedia). https://tyz-yokai.blog.jp/archives/1077252077.html