Houkago Ryoujoku Seitokai ~M Kaichou no Hakudaku Bukkake Gekokujou~

Student president Sera is the main character, and he has a secret crush on Ryou, the vice president.
One day Sera finds Ryou's gym suit and can't help but start masturbating.
After getting caught in the act by Ryou, the secretary, and the accountant, Sera becomes the sexual target of three other people. But then through special circumstances the roles are reversed...

[Edited from DLsite English]