Shin Megami Tensei IV - Demonic Gene

In the Eastern Kingdom of Mikado, in the year 1492, Samurai protect the Luxurors and Casualries who make up its people. Walter, a wild Samurai with self-taught but unpolished skills, wants to improve, while Gina, another Samurai, watches over him with concern. One night, while the two are on watch, they are suddenly transported to an unknown world. There they encounter a tyrant demon far stronger than any they have faced before. The battle against it begins to change the course of both their lives.