After turning 30 as a NEET, Kyousuke was kicked out of his parents' house. That's when Rui, his closest friend, proposes a solution: to get married, then divorce! A guy and girl who've been 'just friends' for around a decade decide to enter a pretend marriage. He's a romantic and she's just a pragmatic girl. A pair unsuited for marriage. What will they discover after 100 days together?