Pedro "Pedoro" Domingo
About
After spending some time as the Great Will of the Macrocosm's boy toy, Pedro escaped and returned home- only to find that his loved ones had already forgotten him and taken up with his neighbor, Gomez.
source: absoluteanime.com
While he is present, he can hardly even be considered a character in the original manga version, since he only has two appearances, the first of which being in a single panel as more of an easter egg than a cameo. The second time he is merely mentioned by name as an in-joke.