Single and middle-aged Toru Negishi registers for a sexual pet website that is said to give its users a free beast girl. Asking for a catgirl while signing up, Negishi is surprised when his request is immediately accepted. Suddenly, a magic circle appears in his living room, summoning a catgirl in heat called Nia. Unluckily for her, she arrives from another world having just masturbated and, therefore, naked. Nia is initially displeased with what happened, but after living with Negishi for some time, she starts to feel sexually attracted toward him.