Zoku Gosenzo San'e

So Gen is back from America and everyone is happy to see him. All of the girls missed him a lot, especially his male organ. But it's to bad his condition has not improved even with all the drugs he took. He wasn't able to cure his illness and to make it worse, a lot of weird stuff started to occur in the school. People are fainting from loss of blood. Oh noes, vampires have appeared. Now it's up to Gen and his friend to solve this mystery.