Dimmy is a ninja Yo-kai. His body is simple, a rectangular figure with a tail instead of legs. His yellow eyes are clear from what appears to be a face hole or mask, which is roofed by what appears to be a metal head band. The rest of his body is a solid purple. He has a sword on his back. He has big hands and long arms as well. He looks like he is coming out of his shadow.
In Yo-kai Watch 2: Fleshy Souls, an alternate appearance of Dimmy can be found, which has a oval placed on his metal headband. This Dimmy has the skill Wavy Body instead of Secrecy.
Dimmy has an excessively passive personality, often expressing a wish to stay out of everything and everyone's way.
In the games, Dimmy causes the Inspirited victim to become completely unnoticed by others around them, even if the victim is directly next to people.
In the anime, Dimmy's possession has a different effect: the Inspirited victim takes on a dispirited appearance with hollow eyes and mouth, and even their physical appearance becomes slightly grey and discolored. They begin to exhibit the same behavior as Dimmy, wishing to be left alone and refusing to do anything asked of them, desiring to stay out of everyone's way. A variant happens to Dazzabel, who although becomes grey, the only thing that seems to happen to her is that her bow falls off, since this Yo-kai lacks eyeballs.
Yo-kai Watch animation series
Dimmy first makes his appearance in Yo-kai Dazzabel & Yo-kai Dimmy when he had possessed Jibanyan. Nate and Whisper noticed the change in Jibanyan's behavior, but don't realize he's possessed. Later, they have trouble with Dazzabel, who has possessed Nate's mother. While his mother is on her way to school, Whisper then reveals that Dimmy was their best chance of defeating Dazzabel and saving Nate from humilitation. It was then that they realize that Jibanyan was possessed by Dimmy, so Nathan summons Jibanyan to get Dimmy. Unfortunately, Dimmy possessed Nate as he is summoned by proxy along with Jibanyan, leaving Dimmy, Nate and Jibanyan despondent and unwilling to interfere with Dazzabel. Whisper ends up forcibly pushing Dimmy towards Dazzabel, which causes his greying ability to affect her and her bow falls off and she loses her umbrella. This change in Dazzabel upsets her so much, her possession is dispelled and her Yo-kai Medal falls out. Dimmy decides to timidly offer Nate his Yo-kai Medal as well.
Befriended(Yo-kai Watch): "Let me be your man in the shadows..."
Befriended (Yo-kai Watch: Wibble Wobble): "I'd like to watch over you from the shadows... If that's OK with you..."
Receiving food (favorite): "Good..."
Receiving food (normal): "Not much to say."
Receiving food (disliked):
"Jimmy" is both a common Western name and a homophone with "ordinary, unremarkable" (Japanese: 地味,Jimi). "Dimmy" is a portmanteau of dim and the male name Jimmy.
In Spanish, "Nomevén" are the words together of the phrase "no me ven"(they do not see me).
Dimmy's appearance is based on that of a ninja. Additionally, both his powers and his thin, flat frame emerging from a shadow could be a play on the expression kage ga usui (literally "having a thin shadow"), which means "barely standing out, fading in the background".
In the box for the Bandai figures, his name is spelled as "Jimii".
A recurring gag has Dimmy and Dazzabel being spotted together.