In episode 11 Sota reveals to his friends that he knew Yuna and that they were friends. Sota added that he was the one who killed her. Yuna and Sota met online when she commented on one of Sota's drawings, and the two of them liked each other's work, so they exchanged emails and continued to write to each other. Setsuna eventually invited Sota to go with her to a Hakoniwa meetup, and the two of them met each other in real life at the train station. At the event Sota and Yuna went onto the second floor of the building to get a better view of the live drawing. Yuna tried to get a better look and was about to fall over when Sota saved her, but in the process Yuna lost her glasses, so Sota offered her to use his glasses. Sota continues telling his friends that he continued to talk to Yuna afterwards, and Yuna kept posting new drawings. Eventually Yuna became popular on the site, and was praised as an up-and-coming artist. Yuna sent Sota a text message telling him that she will be making a video with Shimashima, who is a famous producer, and that she is a big fan of his, so she is nervous. Sota stopped trying to contact her after he felt that there was a lot of distance between the two of them. Yuna was then accused of plagiarism in an online news article and received a lot of criticism in the message board.
She appears in chapter 1, 11 and 20.