Kayano is a girl with a short stature. She has a little frame, hazel eyes, and green hair which is always fashioned in unique, cat ear-styled pigtails. A running gag for her appearance is that she is "forever flat", referring to her not having noticable breast like the other female students in the class.
It was later revealed that her green hair is dyed and her hair is actually black, long, and wavy. Her hazel eyes also became red due to her blood lust. After the events of the Kayano arc, she went back to her cat ear-styled pigtails and her eyes returned to hazel.
After seven years since graduating from middle school, she went back to her original hairstyle prior to joining Class 3-E. Noticeably, her chest has grown slightly.