Returning home from the store, high school student Subaru Natsuki finds himself in a fantasy world. A young man who knows a lot about video games comes to the conclusion that he has been called to another reality. Subaru expects to meet the character who summoned him, but he is attacked by robbers. A mysterious silver-haired beauty and a spirit in the form of a cat come to the young man’s rescue. In gratitude for the rescue, Subaru offers to help the girl find the thing stolen from her. When the goal is already close, the heroes suddenly become victims of a mysterious killer... after which Subaru comes to his senses and finds himself in the same place where his adventures began. Gradually, the young man realizes that he is endowed with the ability “Posthumous Return”. From now on, he will have to go through many trials and save the girl from death. “Even if you forget me, I will remember you.”