Her brother is the ghost Hashira (a demon slayer who os very strong) they lost their parents to evil demons when they where young and her brother became a demon slayer. He told her she was a girl and to weak but she decided to define him and be a demon slayer anyway. She is trying to help her best friend, Lydia, find a demon named Astrid. Yuni is very kind and considerate. She is sweet and loving and always has a smile on her face. Unlike Lydia who is dull and serious.

She is serious. She frowns most of the time. Her best friend Astrid turned into a demon by drinking blood from the demon king muzan. Lydia was attacked by Astrid after she turned into a demon. Astrid blinded her in both eyes so she wears a mask to hide her face. The ghost Hashira came to kill Astrid but Astrid has left. The ghost Hashira offered Lydia a possible life in the demon slayer corps, where the main goal is to kill demons. Lydia excepted thinking that she could meet Astrid aging and talk scenes into her. Lydia’s bestie is the ghost Hashiras sister, Yuni. Yuni is extremely cute sexy and happy. She wants to be a Hashira like Lydia and help the world. (A Hashira is the highest rank in the demon slayer corps)