She is actually named Yukimura Akari, the younger sister of Yukimura Aguri. She used to be a child actress with the stage name Mase Haruna (็ฃจ็ฌ ๆฆๅ). Believing that Koro-sensei killed her sister Aguri, she transferred to Class 3-E under the name Kayano Kaede using her acting skills, trying to look for the chance of killing Koro-sensei.
It's implied that she and Shiota Nagisa are together at the end of the manga.