A member of the 48 demons who pillaged the body of Hyakkimaru, the Ki Oni was a giant tree with the face of a human. Much larger than most demons, the plant-like monster attacked with its hands. If this failed, the creature proceeded to blow its opponent away with its petals and then try to constrict them to death with its hair while they were a safe distance away. All of this failed against Hyakkimaru, though, who used his blades to slice through the hair. Outmatched, the demon buried its head deep in its truck-like body to keep it safe, yet this did little to stop Hyakkimaru from slicing the entire tree in half which killed the demon.