>>5367559>>5387158It's a bit of a strange gag of sorts.
A Jibanyan is made when a cat gets struck by a car (or in Sapphirenyan's case, drowned by sabotage). The town is filled with stray cats and drivers that wait at the last second to stop before hitting pedestrians. Do the math.
While there are a few based on Japanese lore, many of those don't actually appear in the first game. A lot are just made up from modern day events or are just walking puns. More of those Japanese-ish ones appear in the second game.