Jiraiya

Jiraiya is a prominent figure in Japanese folklore, most famously from the tale 'Jiraiya Gōketsu Monogatari' (The Tale of the Gallant Jiraiya). This story, first recorded in the 19th century, tells of a ninja who can shapeshift into a giant toad. He battles his arch-nemesis Orochimaru (who can shapeshift into a giant snake) and his former love interest Tsunade (who can shapeshift into a slug). These characters, often referred to as the 'Sannin' (Three Ninja), have become iconic in Japanese popular culture.

The name itself is believed to be a corruption of 'Garaiya' (我来也), which means 'I came from nowhere' or 'I came to be'. Over time, the character for 'thunder' (雷, rai) was incorporated, leading to the 'Jiraiya' (自来也) spelling, which can be interpreted as 'self-coming thunder' or 'young thunder' depending on the kanji used and context. The association with thunder often implies power and suddenness, fitting for a legendary ninja.