From Seven Seas:
Sunohara Hinata thought defeating the evil overlord and returning to high school in Japan marked the end of his otherworldly adventures. But when Mariabell, his first and most fervent ally from the magical realm, follows him home, his daily life takes a fantastical turn. Just a month after his return, Mariabell, a dark elf with a passionate and slightly obsessive love, declares they’re meant to be together forever. Now, Hinata must navigate the halls of high school while living with a magically jealous girlfriend who takes “school crush” to a whole new level. Join them as they tackle life’s unexpected twists in this exhilarating rom-com adventure.

Serialization of the hentai doujinshi of the same name.