A male and female college student's friends who were picked up try a mission, but it develops into raw sex and creampie

A group of college friends (Erika Inami, Amu Ohara, Yua Kawaei, and Rika Aimi) get picked up and challenged to a game where they can't leave a closed room until they collect 20ml of semen, and it escalates into raw sex with creampies!