Rizelmine

Fifteen-year-old Tomonori Iwaki is an ordinary student with a not-so-ordinary preference for older women—especially his teacher. When he discovers she’s engaged, he trudges home disappointed, only to be met by an unexpected visitor: a 12-year-old girl named Rizel waiting in his house.

Tomonori soon learns the Japanese government has arranged a marriage between them without his consent, turning his everyday school life into something far stranger. Rizel isn’t a typical girl either—she’s a biochemically engineered human—and her creators, whom she calls her “papas,” strike a deal with the Iwaki family: they’ll cover multiple outstanding bills if they’re allowed to stay, setting the stage for Tomonori’s new life with Rizel under the same roof.