Jubokko are a type of spirit (yokai) found in Japanese folklore and are considered dangerous to the living, they are found near battle-fields or places of great bloodshed and are depicted as trees that are surrounded by skeletal remains of past victims, a warning for mortals to stay a good distance least they fall victim to a similar fate.
Jubokko are formed from bloodshed and as such become hungry for blood themselves, much as ordinary plants require water and sunlight to grow the Jubokko requires human blood and will attack any that stray too close, slashing and grappling victims with vicious branches in order to cause severe bleeding, the victim is drained of as much blood as the Jubokko can gather from their corpse before birds and animals take care of the rest, leaving only bones which drop to the ground below and add to the tell-tale bone-pile the yokai forms over time.