Perfect Domination

In this world, people have a secondary sexual characteristic called "Dom" and "Sub." The "Dom" instinctively wants to dominate the "Sub" and the "Sub" wants to submit to the "Dom." Most people are diagnosed in their early teens, but Chigusa's "Sub" characteristic awakens when she is in college. One day, when Chigusa wasn't feeling well, she was rescued by Ryuuji, a senior who lives in the next room, that was she felt her first submissive arousal in front of Ryuuji, her "Dom"...? A destined love between two people who cannot resist their instincts!