Barabanba

Baraba is a corsair of the space that arrives on the Earth, along with her loyal grandpa Dagota (a 300-year-old robot), to escape the pursuers interested in seizing the reward hanging from her head. Their arrival to the planet, however, was not the most comfortable: the crossing of a dimensional barrier creates an imbalance that transforms her into an attractive and naked girl, while Dagota turns into a small monster with tentacles. As soon as she sets foot on the Earth, she is assaulted by Chuta Banba, an impeded high schooler desperately searching for his "first time", with whom Baraba begins a life dedicated to the most unrestrained hedonism.

An OVA adaptation was loosely made from the first events of the story: https://www.animenewsnetwork.com/encyclopedia/anime.php?id=9971