Eien no Aselia

Yuto Takamine and his sister-in-law Kaori are visiting their parents' grave when they are transported to a different world called Phantasmagoria. There, they are captured by the King and a woman named Restina, who take Kaori hostage. Yuto is forced to fight against the world's enemies to ensure her release. The King provides him with a sword named Motomeh to defend the kingdom from spirit enemies. Kaori's freedom is conditional on Yuto's success in protecting Phantasmagoria, marking the start of his mission.