|Voice Actor||Jun Fukushima (Japanese)|
Johnny DeLaCerda (English)
Kosaka appears to be a rather gentlemanly and kind person. He looks rather feminine compared to some of the other male characters in the series. He also appears to be smart, as he was seen tutoring an unnamed girl who was assumed to be his girlfriend.
In episode 3, Kosaka bought Tomoko an umbrella when it was raining, although she did not seem to notice what he had done. In episode 8, Tomoko meets him again. Her cousin, Kī, believes him to be Tomoko's boyfriend after a lengthy lie. After Kī found him with a girl he was tutoring, she demanded an apology for hurting Tomoko, thinking that he was cheating on her. After Tomoko requested that she be left alone with him, Kī found out that Kosaka was not actually Tomoko's boyfriend, she began treating Tomoko differently.
Strikethrough episodes or chapters indicate the character was mentioned but did not make a physical appearance)
- Kosaka is older than Tomoko.