Valkyrie
Heroine of the series and a princess from Planet Valhalla, in the Dolphin Constellation. Once Valkyrie learned that her father was planning a political marriage for her without her consent, she fled to Earth and crash landed on Kazuto's bathhouse. In order to save his life she had to give half of her soul to him, but that process turned her into an 8 year old girl. She can only regain her normal form by kissing Kazuto but it doesn't last long and she normally kisses him in order to protect him. She eventually develops deep feelings of love for Kazuto. Her powers include flight, energy manipulation and defensive shields, plus she gains the Key of Time at the start of the second season, which is capable of a number of things (though before, she already had an object that looked exactly like it). Oddly, early on she's able to use it her child form and adult form, but later only uses it her adult form. When it is later revealed that Kazuto is the one that she will marry, she is overjoyed, but it is difficult for the ceremony to take place since she keeps on reverting back to her child form. At the end of the 3rd season, due to a mishap with the Princess Mural, Valkyrie's older and younger selves split into two separate people. During the 4th season, Valkyrie's former classmates mistake her younger self to be her daughter, until she display knowledge about them convinces them she really is the younger Valkyrie.