Gosenzo San`e is the story surrounding the Hiraga bloodline in which Gen is a part of. Recently orphaned, he moves in to his grandmother's house and unwittingly triggers the Hiraga clan's curse in which nearly every member leads a tragically short life, Gen begins to unravel vaguely remembered memories from a dream he's always had. With the help of an American graduate student, they try to uncover the secret of the Hiraga bloodline. But along the way of finding out the mystery behind, there is lot of sex adventures with his classmates including his American friend and there is a mysterious woman only wants Gen blood and to mate with him.