Kakushite! Makina-San!! summary:

Makina Agatsuma, the school idol, moves into the home of Eita Akutsu, an introverted mechanical otaku. Eita, who has secretly harbored feelings for her, thinks he's hit the jackpot! But it turns out, she's actually a robot made for sexual purposes. Caught off guard by her sudden physical advances, the virgin Eita is at a loss. Furthermore, he finds himself in a frenzy trying to help her maintain her secret identity. A romantic comedy with a slightly risqué mechanical revelation, where hilarity ensues as they try to keep the secret under wraps!