Heikou Sekai no Jibun ga Konomi no Bishoujo de Kuse mo Onajidattanode Koishite Shimatta

Asahi, who has a taste for stories that end badly, strikes up a conversation at a movie theater with a girl named Tsukino and finds she shares the same preference. They part ways afterward, only for Asahi to discover Tsukino at his own home, insisting it is where she lives and showing no awareness of his circumstances. Piecing things together, he concludes she is his own counterpart from a parallel world who has slipped into his. He agrees to help her get home, though neither can ignore how perfectly suited they are to one another.