In a world where people possess a secondary sexual characteristic called Dom and Sub, the Dom instinctively desires to dominate while the Sub longs to submit. Most individuals are diagnosed in their early teens, but college student Chigusa remains undiagnosed until she unexpectedly awakens as a Sub. One day, feeling unwell, she is rescued by Ryuuji, a handsome senior who lives in the room next door. In that moment, before this Dom, Chigusa experiences her first overpowering wave of submissive arousal, beginning a destined love between two people who cannot resist their instincts.

After this intense awakening, Chigusa accepts her identity as Ryuuji’s Dom/Sub partner. As they spend time together, her feelings for him grow beyond the instinctual bond, causing her to question the nature of their relationship. Ryuuji eventually formally confesses to her, and they develop into lovers, enjoying a sweet and passionate time together. However, their happiness is challenged when Ryuuji’s childhood friend and former partner appears, drastically changing the situation.

Later, Chigusa becomes so absorbed in their romance that her studies suffer, threatening her academic scholarship. As she has no financial backing, losing her scholarship means being forced to leave the university, placing their relationship at a major crossroads. Following this, a water leak in Chigusa’s apartment forces the couple to begin living together in Ryuuji’s room. While they enjoy their shared life, Chigusa begins to feel fatigued. Their story continues as they work together at a summer festival stall operated by Chigusa’s part-time job.