Inuyasha the Movie 4: Fire on the Mystic Island (2004) on Netflix

Plot summary

Fifty years after being ambushed on Hōrai Island and marked with four scars, Inuyasha meets Ai, a half-demon child who escaped that island. She asks him to save the other children, whose backs carry the same scars left by the Four War Gods. The island surfaces only once every fifty years. Inuyasha remembers arriving there with Kikyō, who was attacked and lost her blood. As the island returns, Kikyō sets out to investigate, Sesshoumaru leaves Jaken and Rin to confront one of the war gods, and Inuyasha and his companions come under fire from a Thunder Cannon before they reach the shore. Ai leads them to a village where the children live.