Rilakkuma (リラックマ Rirakkuma, a combination of the Japanese pronunciation of relax and the Japanese word kuma for bear) mysteriously appears in the female office worker Kaoru's apartment one day. He is a soft toy bear who has apparently decided to take up residence there. In the picture books, he is often seen dressed up in a variety of costumes. In addition, it is implied that even in his usual appearance, his entire lower body is a costume, which he will often replace when it gets old or dirty (Rilakkuma is frequently seen sitting around waiting for suits that look exactly like him to dry on the clothes line). However, it is not clear whether his head is also part of his costume. His favorite foods are dango, pancakes, omurice and custard pudding. True to his name, he enjoys relaxing and his favorite things include sleeping, lying around, watching television, listening to music and soaking in hot springs.
Rilakkuma is often accompanied by Korilakkuma, who is a smaller child-like white bear with a mischievous personality, and Kiiroitori, a yellow chick who plays a tsukkomi role (considered to be the smarter, more logical one who criticizes others for making mistakes). Kiiroitori is basically the opposite of Rilakkuma because of the bird's hard-working nature and love of cleaning. Korilakkuma frequently plays pranks on Rilakkuma while he is sleeping, such as drawing on him, putting headphones on him and sewing odd color patches on his bear suits. Most of the time, Korilakkuma doesn't say a word, but sometimes she imitates what Rilakkuma is saying.
Korilakkuma also has the appearance of a bear, but also has a red button attached to her chest, and so it seems that she is also not a real bear. However, unlike Rilakkuma, she doesn't have a zipper on her back. Her favorite foods are strawberries, apples and cherries and she loves playing with her radio controlled duck. Like Rilakkuma, she also likes listening to music, particularly at loud volume using her music player.