Kousai 0-nichi Kon desu ga Nani ka?

Despite the nine-year age difference between Koki and Kisa, the two get along surprisingly well. After receiving pressure from both of their mothers, they make a spur-of-the-moment decision to get married (without telling their moms that they've never even dated). The idea of them growing into their marriage sounds rather romantic... but the marriage is actually more like a contract! Kisa's never had a boyfriend and Koki's a total player. Will their marriage work out!? (Source: B-comi)