Yayoi is the main heroine of the series who saved Tetsurou from getting hit by the truck that was owned by Higashikazuno Miya in front of Gokou Academy. She is the one of the members of so-called full-bloomed love, super amazon warriors group called Koi Koi 7. She had a promise that she will protect Tetsurou forever since childhood, but Tetsurou doesn't remember that he had a promise from such a cute girl. She was called "Light" from the girl that has the same name as her.