俺のセフレはカレシ持ち学生会長 ～生真面目JKがイキ狂って妊娠するまでの浮気SEX記録～

The protagonist, Hiyama Tooru, found out about an electoral fraud that was caused by some members of the student council. Using this info, he blackmailed the president, Nitta Iroha, into becoming his sexfriend. Unable to refuse, she accepted on the condition that it will be kept a secret to her boyfriend, Tokuda Issei.

And so Iroha started living a two-timing life, dating her boyfriend Issei while having sex with her sexfriend Tooru.

Taking care not to get caught by the boyfriend, Tooru then thoroughly ravished Iroha and repeatedly, relentlessly cummed inside her, which in turn made her cum a lot that she had to gasp for air.