Kokoro Kosaka (小坂こころ Kosaka Kokoro), is the lead character from the manga series Wallaby. She is a 16-year-old high school student who deeply admired Warabi while he was still alive. She made the stuffed wallaby (Warabi's current body) as a tribute during his funeral. She is somewhat violent and her thinking is simplistic, characteristics shared by her relative Emi.Kokoro likes Warabi more than she lets on, and is disappointed with herself because she often acts cold around other people even though she doesn't really mean to, and while she tries to be nicer, it's not going well. She is also very short-tempered and the person who suffers the most from this is Wallaby himself. By the end of the series, Kokoro is led to think by Lalilalulala that Wallaby might have run away because of Kokoro's behaviour (including forcing Wallaby to sleep in her drawer – even though it was dark and cold in there, refusing to give him any blankets, and rejecting his wish to accompany her on her way to school), however this was not the case as Wallaby had simply been taken by Emi. The character being called Kokoro is ironic since the name means "heart" in Japanese, while Kokoro herself is sometimes thought to be cold-hearted. Though Kokoro initially claims that she has no interest in video games, she becomes a total addict when Wallaby introduces her to them by making her buy a PlayStation for him. Kokoro herself ends up using much it more than Wallaby and seldom allows him to "borrow" it even though it is technically his.
Kokoro lives with her mother and is related to Emi. She is friends with a student of the high school that the events of Azumanga Daioh center upon, and the last time Kokoro is seen is when making a cameo in chapter 9 of Azumanga Daioh during the first cultural festival looking confusedly at the stuffed animals that are for sale together with Osaka and Sakaki, made by their class.
- Kokoro was supposedly born in 1983.
- When the chapter of Azumanga Daioh where Kokoro and Wallaby cameoed was adapted for TV, they were completely replaced by a different character for unknown reasons, though the intention was likely to make the show as realistic as possible by removing supernatural and religious elements (minus Chiyo-chichi). The new character, however, does bear an uncanny resemblance to Kokoro, so it is possible she was kept in, but Wallaby was removed, although her colouring is completely different from the colour inserts in Wallaby, specifically the title page of chapter 6, in which she appears to wear the same outfit.
- ↑ The Azumanga Daioh chapter in which Kokoro visits the cultural festival at her friend's school takes place in November 1999, and Kokoro was 16 at the time. This makes her approximately a year older than the Azumanga Daioh cast, as most Japanese first-year students are 15. 1983 is 16 years prior to 1999.