Nikosen (二枯仙, " Two withered hermit") was a yōkai who decided to devour Inuyasha and Kagome to guarantee his existence as an immortal. Nikosen was previously a monk who started absorbing the life force from trees to extend his life and thus stay an immortal. In the process, he underwent a substantial physical transformation, taking on the appearance of a huge beast with a body made of wood and face of an old man. By slaying Nikosen with the Dragon-scaled Tessaiga, Inuyasha managed to absorb his holy aura and counter the backlash of yōki.