The Nosirs are a trio of Yo-kai triplets. They're all short and wear purple sweater vests, blue bowties, magenta pants, and black eye masks. They have large, thick noses and dirty blond hair. To tell one apart from the other, one of the three wears a small pair of eyeglasses, while another has a large nose hair sticking out of his nose and holds a small vanity mirror.
In the English version, the nosir with the nose hair has been oddly changed to a string of olive colored mucus instead.
They all deny everything and correct people. They aren't used to gratitude or compliments. In the English version of the anime, one of the Nosirs say "Ah ah ahhh." while the other one with the glasses says "No sir-ee bob!" The last Nosir with the snot from it's nose says "That's snot it!"
When Inspiriting their targets, the Nosirs make people second guess the course of action they are about to undertake. In an academic test environment, these Yo-kai can cause unneeded levels of stress.
The leader of the Nosirs is also able to infuse himself into an object, namely the Yo-kai Watch, and is the source of the soundbyte of when the wearer inserts a Yo-kai Medal the wrong way.
Nosirs appear under cars and vending machines in Downtown Springdale and Shopper's Row. They can also be found in Gates of Whimsy. One way to find Nosirs is in the 2nd Quiz Room behind the 40 Gate Globe Gate of Whimsy. They always appear in the top left tree.
Befriended (Yo-kai Watch 2): "We don't want to fight anymore! We don't want to leave you! Nuh-uh-uuhh!"
Loafing: "Can't...move... Eh."
Being traded:"Part with [player's name]? A new friend wouldn't be so bad... No sirree bob!"
Receiving food (favourite): "Don't stop! More!"
Receiving food (normal): "Not bad."
Receiving food (disliked): "No good! Nuh-uh!"
Freed from Crank-a-kai: "Are we free? Nuh-uh-uuhh! You sure about that? Hey, how about we become friends with that guy!? He's going to disagree. Here, just take the medal!"
The Nosirs appear in EP007 while Nate's class is having a multiple-choice test, constantly disrupting the children's attempts to choose answers by their trademark denials. Nate eventually identifies them and confronts them on the rooftop, and attempts to summon Jibanyan (after he and Whisper get the Nosirs' denials stuck in their heads like an earworm) but accidentally inserts the Yo-kai Medal the wrong way around. The Nosirs point this out, and Whisper notes that the Nosirs were actually helpful for once, for which Nate thanks them. This completely throws off the Nosirs, who admit that they're not used to being appreciated. Out of gratitude the first Nosir Inspirits the Yokai Watch so he can tell Nate whenever a Medal is inserted wrongly, and the other Nosirs fly off towards the sunset.
The Nosir Ah-Ah-Ahh's voice appeared in EP008 when Nate puts Roughraff's Medal upside down.
In Yo-kai Watch 2, the Nosirs are the driving point in a Key Quest in Chapter 2, in a similar manner to the anime. They had inspirited Matt during a game of soccer, who was stubbornly denying that the ball he failed to block went in, despite the contrary evidence. The player quickly finds the Nosirs and beats them, allowing Matt to admit that the ball went in. While they were bashful upon giving praise, they didn't want to be friends, and left.
The name "Mitomen" is a cross between the term mitomu (認めん), meaning "don't be sure", and the English word "men". "Nosirs" is a portmanteau of the words no and sirs, or a play on the phrase "no sir", a respectful denial. It can be also be a portmanteau of the words nose and sirs, due to their large noses.
In South America Spanish, "Noseñores" is a combination of the world no and señores (sirs) and also play the phrase "no señor"(Nosir).
In Spain Spanish, "Trillizos No No" is a combination of trillizos (triplets) and no no.
The Nosirs are one of the few Yo-kai that Nathan befriended in the anime that didn't give him their Yo-kai Medal. Rather, the leader of the three upgraded Nate's watch by "fusing" with it instead. This could mirror the fact that Nosirs have not made an appearance in the video games until Yo-kai Watch 2, which is further supported by not being registered in the Yo-kai Medallium in the Recap Time of that episode.