Eien no Aseria - Spirit of Eternity Sword

Yuto Takamine and his younger sister-in-law Kaori were visiting their parents' grave when they were unexpectedly pulled into another world called Phantasmagoria. There, the King and a woman named Restina seized Kaori as a hostage and forced Yuto to fight their enemies. To aid him, the King gave Yuto a sword named Motomeh and tasked him with defending the kingdom from hostile spirits. The only way to secure Kaori's freedom is for Yuto to help protect Phantasmagoria-and so his journey begins.