After her parents' death, sixteen-year-old Fumino Kaji has bounced between relatives' homes with her little brother Teppei and decides to run off rather than be a burden. Her homeroom teacher, Kazuma Ojiro, finds her in a park and, when she half-jokingly asks him to take them in, agrees to marry her so the siblings won't lose their footing. Now secretly a teacher's wife, Fumino has to keep the marriage hidden from school, where exposure would cost Kazuma his job.