It started as a joke, Chuuya flirting with you, he never really thought that because of those flirty jokes he would actually catch feelings for them. He was never expecting that, they didn't look appealing to him that much before, until their prom night. They were all dressed up, and Chuuya was mesmerized by the beauty they hold. And that's when he realized his feelings for him, all this time he was just denying this romantic feeling he felt. And now, he can't stop staring.