Koichi is hospitalized due to a traffic accident and soon falls in love with Nanaka, a pretty nurse. One night, when he walks down a hallway, he finds Nanaka. It seems she does something, but he can't see it clearly. He approaches her and finds that she drinks someone's blood!? Yes, this hospital was established for vampires to be able to get blood legally. Nanaka notices him and tries to erase his memories. However, she is an unskilled vampire and mistakenly changes him into a vampire. He is now a vampire, but there is something wrong with his body. He needs to release semen regularly to prevent his sexual desire from exploding. How can he release his semen? Of course, having sex! It seems to take a week before his medicine is concocted. Nanaka, Reika, Nanaka's older sister, Kanade, a patient next room, and Mao, his old friend decide to take care of him... [From Himeya Shop]