TRANSLATION: Okiku bug
HABITAT: wells around Himeji Castle
APPEARANCE: Okiku mushi are caterpillar-like yōkai with the torso of a human woman. They are called Okiku mushi because it is believed they are born from the vengeance of Okiku’s ghost, from the story Banchō sarayashiki.
ORIGIN: According to her story, the servant girl Okiku was murdered by her lover. Her body was tied up, she was tortured, and then her body was discarded into the well of Himeji Castle. After her death, a number of strange occurrences were blamed on Okiku’s ghost. One of these was the sudden proliferation of a certain type of caterpillar—known in English as the Chinese windmill (Byasa alcinous). The chrysalis of this butterfly was thought to look like a tied up woman’s body, which the locals immediately associated with Okiku’s story. It was believed that her spirit must have come back as these bugs, spawned by whatever part of her grudge remained on this world.
While this insect is commonly known as the jakō ageha in Japan today, it is also known by its nickname Okiku mushi. This is in part due to the popularity of the Okiku story, as well as to the clever marketing of the local shopkeepers around Himeji Castle, who during the Edo period sold the chrysalises of these insects as souvenirs to tourists at the shrines near Himeji Castle.