From MangaHelpers:

Dozuru is a great auk, the first bird ever to be referred to as a "penguin." He leaves his few remaining family members to search for a better place for all of them. Unfortunately, he is first picked up by the sadistic Yoshie Tanaka. She tells him that his species is extinct, and, to keep from ending up a lab rat, he'll have to pass as a weird penguin. After some cruel surgical alterations, Dozuru is on his own once again.

This time, he is picked up by the siblings Hareru and Harema Haruno. Harema, the older brother, adores pets and eagerly takes in the ailing penguin. His little sister is more reluctant, but gives Dozuru his new name "Kushi P" (a name based on the assumption that they'll eat him eventually). It seems like everything is going well for the little "penguin." However, Kushi P has started a habit of slaughtering the other animals around him, and Yoshie is still lurking in the shadows. Will Dozuru/Kushi P ever be able to rejoin his family!? [tethysdust]