One morning Sunao Moriyama, a male junior high student, finds a small, cute creature in his refrigerator. During breakfast, Sunao looks down at what he is eating, a bun with potato and mayonnaise filling, and decided to name the creature Potemayo. Sunao takes Potemayo to school with him and she is an instant hit with his classmates, especially the girls. While they are at school, another similar creature comes out of Sunao's refrigerator and makes its way to a park where Sunao and his class are spending an art class. Kyō Takamimori, one of Sunao's classmates, finds the creature and names her Guchuko. Unlike Potemayo, Guchuko is aggressively antisocial and shoots searing energy beams out of horns on the sides of her head when she is confronted.
The four-panel comic strip manga series, written and illustrated by Haruka Ogataya, originally started serialization in the Japanese manga magazine Moeyon on July 9, 2004. In October 2005, the series moved to the seinen magazine Comic High! and continued until January 22, 2011. Five tankōbon volumes have been released in Japan, published by Futabasha.
An Internetradio show entitled Kana's and Ayumi's Mayonnaise Radio was streamed between June 29, 2007 and March 28, 2008 every Friday on Beat Net Radio! and Lantis Web Radio. The author of the manga had made two guest appearances, and also the editor of Comic High, Kyōichi Nonaka, had made an appearance. The show was hosted by Kana Hanazawa, who played Potemayo in the anime, and Ayumu Tsuji, who played Guchuko in the anime.
Anime
A 12-episode anime series adaptation was produced by the animation studio J.C.Staff, directed by Takashi Ikehata, and written by Yasunori Yamada. It aired in Japan from July 6 to September 21, 2007. Each anime episode usually contains two sub-episodes with separate storylines, ending with 24 sub-episodes by the end of the series. Additionally, there are short animated specials released on the DVDs which are additional sub-episodes to the series. There will be one special per DVD, ending with six total specials. The anime's opening theme was "Katamichi Catchball" by Mosaic.wav; the maxi single containing the opening theme was released on July 25, 2007 by Lantis. The ending theme was "Utatane" by Chata; the ending theme single was released on August 22, 2007, also by Lantis. The anime's original soundtrack, composed by Tomoki Kikuya, was released on October 10, 2007.