Momiji is the younger sister of Kaede. She is in middle school, and is in the same class that Mahiro enters when they reenter school. Momiji likes to dress, look, and act as a tomboy, and many times she is taken for a young teen/tween boy. However, Momiji gives no indication that she is in any way a transgender tween. She appears to only be gender non-conforming. However, she can be quite feminine in appearance on select occasions, like when she wears the middle school female uniform, a cute jumper dress, to school. She forms a strong friendship with Mahiro, and helps Mahiro navigate the middle school academic and social challenges of school. Many times she comes to Mahiro's defense when Mahiro is bewildered or frightened by somebody or something happening at school, or if it is perceived that the boys are picking on her. She is part of a tight-knit social circle foursome of friends at school, with the other three girls being Mahiro, Asahi, and Miyo-chan.