Yuri Kotobiki

Personality
Yuri comes off as smart, slutty, beautiful, and carefree. She is easy to get along with and likes to have fun. Despite her popularity, Yuri has low confidence and a tendency to become lonely, especially in her relationships. As a result, she uses sex with different men as a means to fill her loneliness. Even as she fell for Kido, she continued having sex with another man, and lied about him being her father.

In truth, that other man was her real boyfriend, and she was actually cheating on him with Kido. She felt like he only used her as a sex accessory or trophy girlfriend, and at first she only went with Kido because of the attention and care he gave her. After Kido saw her having sex with her real boyfriend on his birthday, he dropped a present that he was going to give her on the floor near the door, which she noticed. Feeling regretful, and after realizing how she genuinely fell in love with Kido, Yuri broke up with her boyfriend and tried to make amends. But Kido rejected her, much to her horror. She begged him not to, but he broke up with her in tears anyway; his loneliness completely returned as he felt isolated without the girl he came to love and no real friends to speak of otherwise.

Nonetheless, she still has feelings for Kido, but she matures, and decides to focus more on her career rather than spend her time joined to the hip of a guy. She takes the time to reconcile with Kido, who later admits that he's glad she was his first girlfriend. Even ten years later, Yuri still teases Kido, who takes it amicably.

Plot
Tatsuhiko’s first girlfriend. They had a good relationship at the start but ended abruptly as Kido found out with the help of Emiru by following her around town and finds she was cheating and using him for time until the weekends, in which she has relations with another man. She loves him very much and spends a lot of time being intimate with him. Because of this he breaks up with her, which leaves her devastated. She and Kido avoid each other at school afterwards.

After Emiru disappears, she calls Kido, being their first contact since their breakup, and asks him if he would be willing to meet her at a restaurant they used to go to together. When Kido asks her about the man she cheated on him with, Kotobuki reveals that she broke up with him the night she came to Kido's apartment. She tells Kido how she is concentrating on her dream and not love, which prompts Kido to tell her that he's glad he fell in love with her. He also calls her "Yuri-chan", his affectionate nickname for her, for the first time since their last passionate encounter. Kotobuki turns around, saying she's not good with these sort of things, bidding him farewell. She leaves smiling with tears running down her face, now on good terms with her ex