Inuyasha the Movie 4: Fire on the Mystic Island

Hourai is an enigmatic island that appears only once every fifty years. Some claim it holds the secret of immortality, while others believe it brings ruin to those who seek it. When Inuyasha and his companions rescue a half-demon child named Ai from a monstrous pursuer, they learn she fled Hourai and is somehow connected to Inuyasha. She pleads with him to save her friends, who are imprisoned by the Four War Gods-a group of ruthless demons Inuyasha knows all too well. Upon arriving at Hourai, the group finds only a few orphaned children left on the island, marked by a curse that binds them as sacrifices to fuel the Four War Gods' power. With no way for the victims to escape, Inuyasha's only choice is to confront the demons. But defeating them won't be easy-their overwhelming strength means the group must rely on cunning and teamwork to stand a chance.