Ryo-chan, trying to take pictures of Nishi.
The second, and most probable love interest for Joichiro Nishi in the manga series. She is only referred to as 'Ryo-chan', as shown in the name section of her cellphone in the Gantz: Nishi SP (special).
Here, we learn she is in the next class over from Nishi (and as such, was not killed by him later on after his class throws him out of the window). She is shown following Nishi, because a group of people at their school highly disliked the male, saying 'he kills cats'. She followed him, in hopes of taking pictures and proving once and for all whether or not he did so.
But when a cat did in fact come in contact with him and he slipped into an alley, she followed him, but he had disappeared, using his Gantz suit. When he revealed himself and questioned her, she confessed non-existant feelings for him as a way of brushing off her stalking, to which he seemed generally
uncaring. Despite this, it can be hinted that Nishi and her are going out. This is due to the reaction of her two friends when she reports what had happened and her friends tell her to go and have fun with her new boyfriend.