InuYasha the Movie 4: Fire on the Mystic Island

"InuYasha the Movie 4: Fire on the Mystic Island" (映画犬夜叉 紅蓮の蓬莱島) is a 2004 Japanese animated fantasy adventure film directed by Toshiya Shinohara and written by Katsuyuki Sumisawa. It is the fourth and final film in the InuYasha series. The story revolves around Hōrai Island, a mysterious island that appears every fifty years, and the half-demon children living there, who are enslaved by the Four War Gods. When Inuyasha and his companions rescue Ai, one of the children who escaped, they learn that the Four War Gods are using the children as sacrifices to enhance their power. Inuyasha's group then travels to Hōrai Island to confront the Four War Gods and their Kikyo doppelganger, a challenge linked to events that took place fifty years before. Ultimately, Inuyasha and his friends defeat the Four War Gods, save the children, and the island disappears, putting its myth to rest. The film's theme song is "Rakuen" by Do As Infinity.