Mizue is Tsuchiura's former girlfriend. She met Tsuchiura, Tsukimori and Kahoko by accident at the train station. She also once mistook Tsuchiura, Tsukimori and Hihara as Kahoko's boyfriend. She once went out with Tsuchiura during middle school, but went separate ways after three months. She said even though she was the one to break-up the relationship, but was still hurt by it, even now. She commented that maybe she was the type that was to be pampered. The reason was Tsuchiura always called her by her last name, but Mizue called him in his first name instead. She noticed that when they are together, he never looked happy and which Kahoko realised during their meeting at the garden café. She stated that all she ever wanted is for Tsuchiura to call her by her first name, which he does when they broke up.