Kirio, Shirou, and Eita had been close friends since childhood. Kirio held deep feelings of love for Eita, but was devastated when he began seeing someone else. Kirio believed that he and Shirou were going through the same heartbreak since he thought Shirou also had a crush on Eita. However, one day, Shirou revealed that his affections were actually directed towards Kirio. Since Shirou's confession, Kirio has been more aware of his feelings whenever he's around him.