7 Years Later

In the world that Assassination Classroom takes place, the population has drastically decreased. Because of this, there is an order placed by the government called the Soulmate System. At the ripe age of 18, these new adults are to sign a paper with their chosen 'best friend.' When one is engaged to another person who has also signed this contract with their 'best friend.' The people this engaged couple has signed the paper with must marry each other, due to the law. The system expects an increase of babies, with the greater amount of marriages, where couples are in close contact.

Kayano and Nagisa are engaged. Their best friends, Karma Akabane and Y/N L/N, are forced into an arranged marriage after a broken relationship in the past.