Rizelmine

Iwaki Tomonori is a 15-year-old boy with a particular attraction to older women. He's disappointed when his crush, a teacher, becomes engaged, but that's soon overshadowed by the government's surprise announcement: they've married him off to a 12-year-old girl named Rizel. What's more, Rizel is a biochemically engineered human created by a team of scientists who will pay off Iwaki's parents' debts if they can keep her at their house.