The anime series UFO Princess Warukyure, or UFO Princess Walkyrie, narrates the tale of an alien princess who unintentionally crashes on earth. Kazuto, who is striving to maintain his grandfather's communal bath, witnesses the incident. As destiny would have it, a portion of Princess Walkyrie's essence transmigrates to Kazuto, making it obligatory for her to stay with him. However, things escalate when the princess's debilitated soul causes her to revert to a juvenile state both mentally and physically.