Месоуса

Mesousa is a parody of the "cute mascot" type characters often seen in anime, with one huge difference: Mesousa has a severe case of depression. His lack of thumbs makes everyday tasks almost impossible, further deepening his depression. Practically useless in every way, Mesousa serves as the slapstick of the series, being blown up in one episode and having his legs broken in another, all without complaint. He also appears to be somewhat infatuated with Ichijou. His "tastiness" stat is a reference to the mascot character Menchi from the parody anime Excel Saga.

Mesousa is not Becky's pet, but, rather, her companion who tries to help her in class such as getting and holding the footstool for her while she stands on it to write on the blackboard. His name derives from the combination of "meso meso," a Japanese psychomime for whimpering, and "usagi" (兎, "usagi"?), which is Japanese for "rabbit". (Source: Wikipedia)