Sweet ☆ Switch: Majiwaru Shisen de Torokeru Karada

Based on the erotic game by Ammolite.

There is a reason why Ryuuichi, an ordinary student with neither physical strength nor courage, is feared by everyone around him. It is because of his exceptionally vicious eyes. That day, he was stopped by a teacher and given a lecture, but then Sara, the student body president, passed by and took him away. As it turns out, Sara has a proclivity to go wild when her eyes meet Ryuuichi's, and she tells him that the only way to get used to her gaze is to have sex with her every day. When Fumino, the secretary of the student council, finds out about their secret, Ryuuichi is forced to have sex with Fumino, who begs him to cure his anthropophobia...

(Source: parabook, translated)