Kosaka appears to be a rather gentlemanly and kind person. He also appears to be smart, as he was seen tutoring an unnamed girl who was assumed to be his girlfriend.
In Episode 3 Tomoko encounters him and a friend as she waits out a rain storm at a bus stop after her umbrella broke. She tries to impress them, fails as only Tomoko can, then leaves briefly to compose herself. When she returns, she finds them gone, When she falls asleep, Kosaka returns having bought Tomoko an umbrella. In Episode 8, Tomoko meets him again. Her cousin, Kiko Satozaki, believes him to be Tomoko's boyfriend after Tomoko's lengthy lie. When Kii finds him with a girl she demands an apology for hurting Tomoko. Discovering this, Tomoko requests that she be left alone with him and very formally apologizes. Kii sees this from a distance, realizes that Kosaka is not Tomoko's boyfriend, and begins treating Tomoko differently. Thus far, Kosaka has never made another appearance in the manga.
Kosaka has a thin build, gray eyes, pale skin, and short black hair.
Strikethrough episodes or chapters indicate the character was mentioned but did not make a physical appearance)
Kosaka has reached out to Tomoko to show her some kindness. After Tomoko formally apologizes for claiming to Kii that he was her boyfriend, he has not appeared in the manga.
- Kosaka is older than Tomoko.
|Female Characters||Tomoko Kuroki | Yū Naruse | Mrs. Kuroki | Kotomi Komiyama | Megumi Imae | Kiko Satozaki | Ogino | Yuri Tamura | Masaki Yoshida | Mako Tanaka | Emiri Uchi | Hina Nemoto | Akane Okada | Asuka Katō | Shizuku Hirasawa | Akari Iguchi | Sayaka | Koharu Minami | Hikari Itō | Shiki Futaki | Miyazaki|
|Male Characters||Tomoki Kuroki | Mr. Kuroki | Kakinuma | Yoshinori Kiyota | Kosaka | Hatsushiba | Suzuki | Jun Ishimine | Homeroom Teacher | Art Teacher | Aomatsu | Yocchan | Nico Tanigawa | Wada|
|Minor and Unnamed||Minor and Unnamed Recurring Characters|
|Manga Volumes||01 | 02 | 03 | 04 | 05 | 06 | 07 | 08 | 09 | 10 | 11 | 12 | 13 | 14 | 15|
|Anime Episodes||01 | 02 | 03 | 04 | 05 | 06 | 07 | 08 | 09 | 10 | 11 | 12 | OVA|