Misao is a fairly skilled ninja from the Oniwabanshū clan of onmitsu previously based in Edo. Her weapons of choice are the kunai. Misao is about sixteen years old when she is first introduced, though she appears younger.

Misao is the granddaughter of the former okashira of the Oniwabanshū. She was in the care of the last leader of the Oniwabanashu Shinomori Aoshi until Aoshi, Han'nya, Shikijō, Beshimi, and Hyottoko left her to Kashiwazaki Nenji, also known as Okina of the Oniwabanashu, when she was eight. She and Okina had a strong bond, though in Misao's mind, Aoshi remained the best. She also had a special affection for Han'nya, who was always the one to take care of her and taught her how to fight. When she heard that Aoshi was in Tokyo, she went to search for him and runs into Himura Kenshin on the way back to Kyoto.