Ryuuzetsu (竜舌, Ryūzetsu) was a kunoichi that appears in Naruto 5: Blood Prison. Ryuuzetsu was a childhood friend of Mui's son, Muku. Just like Maroi, she also had an undercover mission in order to investigate Mui as to the disappearance of Muku when he was still young.
(Source: Narutopedia)