Ouga

Ouga is a former Inner from the organisation Kara. As a former Inner of Kara whose body was modified with Scientific Ninja Tools by Amado, Ouga was regarded as being completely monstrous in terms of power and ability. However, only her brain was augmented and she doesn't consider herself suited for combat. Disguised as "Yatsume", she joined the Thunder Train with several passengers. Dropping the Yatsume facade, she revealed herself as the true Ouga, explaining who she was and what she wanted. Due to her brain damage which left her without a desire for survival, she wanted Boruto to break the genjutsu and free everyone, but as the construct collapsed around them, Boruto refused to give up on her. Reaching out to Boruto when he reached out to save her was enough to cause her to leave the genjutsu herself, where she proceeded to free everyone. She left before everyone came to and left Shamo a letter addressed to Boruto, which he delivered. In it, she teased him about trying to guess the dream that sparked in her and promised to visit him one day. (Source: Narutopedia)