Taken from Youkai website
BEHAVIOR: Despite their apparent cuteness, keukegen do not make good pets. They are actually a kind of minor spirit of bad luck, disease, and pestilence. They bring sickness and bad health to those whom they live near. Generally they try to avoid human contact, being shy by nature, and are rarely seen. However, their proximity is apparent when members of a household mysteriously begin to contract sickness or bad luck. They are easy to avoid, however, as keep away from clean, kempt houses.

ORIGIN: Keukegen’s name is a pun. It is commonly written with characters that mean “a hairy fluffy sight,” but can also be written with different characters that mean “rare and dubious.” Unsurprisingly, these creatures are rarely seen directly, and those who claim to have seen them are often accused of imagining it. Though while keukegen may be hard to see, the sickening effect of their presence is very obvious.