The story opens with Kokoro remembering Warabi, her recently deceased classmate whom she admired greatly along with many other girls of her school. She is at school and pretends to talk to Warabi about the stuffed wallaby she made, and leaves it by his old desk, when she suddenly discovers that the doll is talking and telling her that he is in fact Warabi who has taken over the doll's body. Since his parents also died, Warabi has to be taken care of by Kokoro, but she musn't reveal the truth about his identity to anyone since Warabi's guardian angel, Lalilalulala, won't get promoted if anyone finds out that she failed her mission of bringing happiness to people like Warabi. Most chapters take place on successive days, so that the series follows, almost literally, the characters' "daily lives".
The manga was published in the magazine Game-jin between December 1998 and the summer of 2000, which means that it was partly published simultaneously with Azumanga Daioh's publishing in Dengeki Daioh. The main character, Kokoro Kosaka, makes a cameo appearance during the first cultural festival of the series, looking at the stuffed animals sold by Osaka and Sakaki and talking to them. This is the last time Kokoro is seen and in the final chapter of Wallaby, Kokoro says that she will visit her friend's school which is what she does in Azumanga Daioh.
See List of Wallaby chapters. The manga was written and illustrated by Kiyohiko Azuma, and published in Game-jin (which started out as a bimonthly magazine and later became a quarterly magazine). The chapters have not been collected in any tankōbon volumes due to the manga being stopping after 8 chapters.
- azumakiyohiko.com, Kiyohiko Azuma's personal website.