To increase the birth rate, marriage relationships are regulated by the Japanese government. The Ministry of Health, Labour and Welfare assigns a suitable life partner to young people on their 16th birthday. Love is illegal in this world, those who defy the government face harsh penalties. Yukari Nejima is an average teenager. Shortly before his 16th birthday, he confesses his feelings to his childhood sweetheart Misaki, who reciprocates. But shortly afterwards he is assigned the girl Ririna as his partner. Ririna is equally unenthusiastic about the assignment and allows Yukari to have an open relationship with Misaki. This is how she wants to learn what love is. While the youths discover their feelings, they have to keep up appearances before the government all the time ...