Eien no Aseria - Spirit of Eternity Sword - S01

Yuto Takamine and his younger sister-in-law Kaori were visiting their parents' grave when they were suddenly summoned to another world, Phantasmagoria. The King and a woman named Restina took Kaori hostage and ordered Yuto to fight their enemies. Then the King gave him a sword called Motomeh to protect their kingdom from enemy spirits. Kaori will only be freed if Yuto helps protect Phantasmagoria. So Yuto's journey begins...