雌のハムスター・エビちゅの飼い主は、浮気性の彼に振り回されている独身OL。彼女のことを「ご主人ちゃま」と呼んで慕っているエビちゅだが、家事全般を任されていたり余計なひと言を発してキツイせっかんを食らったりと、なかなか扱いは悪い。それでもなお、エビちゅはせっせとご主人ちゃまに尽くすのであった。Ebichu the hamster seems like the perfect house pet: she cleans, shops, cooks, does laundry, and anything to please her master, known only as "Office Lady" (OL). Unfortunately, OL and her unfaithful boyfriend, combined with Ebichu's uncontrollable exuberance and love for ice cream, often earn her severe and bloody punishment. However, Ebichu doesn't seem to mind the abuse if she achieves her goal of making her beloved master a little bit happier.