About the Destiny Lovers Manga Volume 4 (Mature)

For high school student Fujishiro Kosuke, things are getting grim. He's been held for over a week in a strange prison staffed by beautiful wardens who seem intent on one thing and one thing only: convincing him and the other prisoners to give up their virginity! They boys held out for as long as they could, but one of them has finally fallen -- and one of the wardens revealed what they'd suspected all along. If any of the virgins give in to their captors' lustful desires, they'll be killed!