先輩がフィアンセ！？

Our protagonist is in for a rude awakening once he starts another year at high-school; his mother tells him that she has arranged a marriage for him with a fellow classmate. The girl’s name doesn’t ring a bell until he realizes that she is the student infamous for being a hard-assed class-rep! To ensure the fact that the parents are insane, they arrange their cohabitation together as a sort of “husband & wife training”. While the parent’s retain their blind idiocy and leave them alone in a house, we can all imagine what could happen when you stick a man and a woman together under one roof (and under such pretenses).

[From White Masq]