Mashiro once interrupted the Kamikami Kaeshi ceremony when she was three year old. The gods flew away, and she was punished by being the one who has to host then imn her hair. She was Locked for thirteen years in her room, where she did not grow physically, only her hair grew, which she was not allowed to cut. Mashiro did not know anything about the outside world, only what she read in books, making mistakes as confusing Uno and Seno with sheeps. When Uno and Seno escaped from her room she followed then, and so she first stepped outside, only to have Hayate and her aunt to see her; and want to lock her again in her room. She did not want that to happen, and she wished not to be in said room ever again. The, the god of fire appeared and granted her wish, making her body also to grow to a normal sixteen-year girl body in seconds.
Mashiro, in Japanese (or literally this word is japanese), means Pure White. Her surename, Kamitsuka, means Bite.