In a future where Japan struggles to combat its low birth rate, the Japanese government implements the "Yukari Law": a matchmaking system based on genetic compatibility for children who have turned 16 years old. Hailed as "The Red Threads of Science," it is a well-accepted policy, promising a fulfilling life to those who comply and penalizing the ones who defy.

Almost 16 years old, time is short for Yukari Nejima. He decides to confess to his crush, the beautiful and popular Misaki Takasaki, who he has been fond of for the past five years. To his surprise, Misaki reciprocates his feelings. But just as the pair are sharing an intimate moment, Yukari receives his government notice. He is to be married to his government-assigned partner, the blunt Ririna "Snooty" Sanada, and is now thrown into a world of love and lies, as he desperately clings onto his feelings.