InuYasha Movie 4: Guren no Houraijima

Once every fifty years, the mysterious island of Hourai emerges from the mist. When Inuyasha and his companions rescue a half-demon girl named Ai, they learn that she escaped the island and that several other children remain trapped there beneath the rule of the Four War Gods.

Inuyasha has encountered Hourai before, and returning forces him to confront memories he would rather leave buried. The children carry cursed marks that bind them to the island, while their captors intend to use them as sacrifices. To break that cycle, Inuyasha, Kagome, and their friends must challenge four demons whose power has terrorized Hourai for generations.