湯ヶ先町に住む月島亮史は、夜間バイトで生活費を稼ぐ何の変哲もない青年にして、その正体は吸血鬼。使い魔の猫・ツキと共に、それなりに平穏な毎日を送っていた。　そこに突然現れた幽霊少女・雪村舞、そしてシスターのレレナ。居候同然に月島家に住みついてしまった二人の少女は、亮史を数々の騒動に巻き込んでしまう。さらに正体不明の化け物＜蜘蛛＞なるモノも現れて……。

The first commander of the famed Shinsengumi samurai police force, Serizawa Kamo has seemingly gone mad in pursuing his own agenda during the final days of the shogunate era. When not trading blows with the likes of Sakamoto Ryoma, Nakaoka Shintaro and other loyal servants of the state, Serizawa indulges himself in the earthly pleasures of, women, sake, and money. Forced to plot an assassination against him are Kondo Isamu, Hijikata Toshizo and Okita Soji - members of the same Shinsengumi unit. Enter the world of these legendary heroes as they each struggle to come to terms with the tumultuous period of transition between the long-standing rule of the Edo shogunate and the new Meiji era.