Allnyta has pale blue skin. It always bears a sharp-toothed grin, and its red eyes are always half-shut with dark bags underneath them. It has a dusty-red mullet and two horns of the same color. Tiny yellow stars float around its head, and purple clouds float around its orange moon-shaped tail. It wears a navy blue robe and a white coffee cup on its head. It sits on a lavender colored cloud and carries a Nintendo 3DS with it all of the time.
Its English name, "Allnyta", is a mispelling of the phrase "pulling an all nighter" which means staying up all night.
Its Spanish name, "Cafeíno" is a corruption of "Cafeína" (Caffeine) what takes away sleep.
"Noctambill" is a joke on the french word "noctambule", night owl in english.
Allnyta, along with its pre-evolved form Wydeawake, and Failian, are the few Yo-kai with their Japanese names written in upper case Italic letters. In the games, these names carry their respective furigana above each syllable to make their pronunciation easier to Japanese players.