"Menchi" is the name given to a small, stray female dog that Excel finds in the street in episode 1 of the anime and decides to bring home with her as an "emergency food supply". Menchi spends most of the series trying to escape from both Excel and Hyatt (who despite her personality, also sees Menchi as only food rations) and even succeeds on a few occasions, but always manages to cross paths with Excel later on and ends up recaptured. While Menchi can't speak aloud, she is shown to understand human language and is absolutely terrified of both Excel and Hyatt, for obvious reasons. Similar to Sumiyoshi, Menchi's thoughts and feelings will occasionally be expressed through text effects on the screen.

Episodes 10 and 19 in particular are focused almost exclusively on Menchi, both episodes being modeled after children's stories about talking or otherwise extraordinary animals. The earliest record of Menchi is a flashback in the anime, showing her previous owner - a kindhearted old man who may or may not have taken care of her in lieu of younger owners. Throughout episode 10, Menchi has frequent flashbacks of her previous owner, and longs to find him and be happy once more. Through these flashbacks, it is shown that the old man set Menchi free because he was worried about his own limited time on this earth... it's not until later, however, that she abandons this hope after the old man betrays Menchi and her canine companions, reluctantly returning to Excel and Hyatt at the end of the episode. Her reason in doing so is debated, however, as she continues to makes numerous escape attempts throughout the rest of the series.

Menchi also sings the ending credits theme at the end of each episode in the anime, bar the final episode, in which her role is reversed with that of the girl who translates Menchi's dog lyrics in the previous closing sequences.

"[Menchi's] breed, though not stated in the anime or manga, appears to be a small Shiba Inu, a baby Akita Inu, or a Hokkaido." (Wikipedia)