Usapyon wears a yellow spacesuit that has rabbit-like ears on the hood, and he carries a small orange ray gun modeled after a carrot. He also has a blue jet pack attached to his back, along with a smoky-looking purple tail that resembles a burning flame. When in Invader Mode, a glass plate flips over his face, black smoke fills his helmet, and his eyes turn red that is activated when pressing the buttons at the bottom.
In Emperor Mode, he gains red armor and a teal-green cape. His Invader Mode-like eyes are also noticeably thicker and gain a eyelash-like spike. His tail and jet pack will turn into a dark maroon color. Usapyon's gun also changes in color to reflect Emperor Mode.
Without his spacesuit, he is revealed to have an otter-like appearance with round ears, a wispy strand on it's forehead, and white tips on his feet and hands. He also wears a red scarf around his neck with a star-and-stripes pattern on it, with black underwear saying "USA", referencing his origin as a 'Merican Yo-kai.
Usapyon is a serious and abmitious Yo-kai, usually showing signs of frustration when things don't go to plan. He is easily annoyed if someone provokes him. He is also persistent, as he does not like to admit he's wrong until proven otherwise. He is shown to be very intelligent because of his huge flare for rocket science. This can cause him to act arrogant and rude, sometimes even to the point of brashness. When provoked enough, Usapyon will activate his Invader Mode, which consists of him chasing and trying to shoot the one who angered him, showing a rather violent side to him.
Even though he can be mean and witty at times, Usapyon genuinely cares for those who he holds a close bond with and seems to suffer from monophobia. This is most likely because he was depressed back when he was alive before meeting Doctor Hugley, as no one ever cared for him beforehand. Throughout the series, Usapyon is shown to also incredibly determined when focused on a task, almost stopping at nothing to get the job done. Whenever someone, mainly Hailey Anne, rambles on about something that is uninteresting to him, Usapyon will still listen to whatever they have to say, despite being bored.
In the English dub of the Yo-kai Watch anime, he is shown to speak in a young Texan accent, reflecting his origin as a "space cowboy".
Usapyon uses a laser gun officially referred to as the "Bunny Blaster", which shoots out a blue laser beam from a distance. The beams he shoot appear to be made of electricity, since in one episode when he shoots Hailey's chair. it gets zapped by it, revealing its "skeleton."
Usapyon has another mode known as Invader Mode (Japanese: ベイダーモード,Beidā Mōdo, Vader Mode) where a black glass plate flips over his face, black smoke fills his helmet, and his eyes turn red. He also carelessly shoots multiple red beams targeting towards his annoyance that give a slightly stronger power than his regular laser gun ammunition. In the anime, he presses and holds both gray buttons on the cheek area on his helmet.
When his rage is at its peak, he transforms into Emperor Mode (Japanese: エンペラーモード,Enperā Mōdo) by pressing the yellow buttons on top of his helmet, where he gains red armor and a teal-green cape while his gun also changes in color. His Invader Mode-like eyes are also noticeably thicker and gain a eyelash-like spike. His strength is also significantly increased.
Usapyon can change his Elemental Technique's attribute depending on the costume his is wearing and were considered Rare Yo-kai. In Yo-kai Watch 3, they were later made separate Yo-kai, along with his Usapyon B costume, and stripped them of their Rare Yo-kai status, except for Usapyon B.
Football Gear (Japanese: アメフトスタイル,Ame-futo Sutairu) changes his attribute to Fire and gives him the Soultimate move Quarterback Sack. In Yo-kai Watch 3, Football Gear instead has a Lightning attribute. The Medallium Bio for this gear states: "Usapyon put on some 'Merican Football Gear, hoping protect himself from big hits up in space."
Racing Gear (Japanese: ドライビングスタイル,Doraibingu Sutairu) changes it to Lightning and gives him the Soultimate move Road Rage. In Yo-kai Watch 3, Racing Gear instead has a Wind attribute. The Medallium bio for this gear states: "Usapyon put on some Racing Gear. It seems it's important to be able to drive really fast up in space."
Scuba Gear (Japanese: マリンスタイル,Marin Sutairu) changes it to Water and gives him the Soultimate move Scuba Splash. The Medallium bio for this gear states: "Usapyon put on some Scuba Gear, in case he need to swim around underwater when up in space."
GI Gear (Japanese: ミリタリースタイル,Miritarī Sutairu) changes it to Earth and gives him the Soultimate move Air Support. The Medallium bio for this gear states: "Usapyon put on some survival gear, ready for whatever harsh environments await him up in space."
Usapyon used to be an otter named Danny (Japanese: ちび,Chibi), who ended up in a rabbit farm for an unknown reason. One day, he was selected by NASU of Doctor Hughly to be the first animal to go to outer space but during the engine test, Danny was inside the rocket and began to panic only for him to die in the rocket explosion and become Usapyon.
Usapyon believes that when he was a test subject, he was treated well, but eventually relearned he was kept in a cage and fed whenever the scientists told him to.
Usapyon first appears in the Sub Mission called Lone Blaster!
He appears to be very strong, since even strong Yo-kai like Robonyan F and Sproink run from him. However, as Sgt. Burly states, Usapyon is a far-away attacker that is dependent on attacking from afar and is nearly useless up close in battle. Usapyon can activate Emperor mode, and when he does, he gains the ability to fly and has a more powerful beam.
Even though Usapyon was initially removed from the American, European, and Taiwanese versions of Yo-kai Watch: Wibble Wobble (with the exception of the intro), one of the Medal Point rewards that the player can get is the title "Pyon". His favorite food, Donuts, was also added to the game before his addition, despite no other Yo-kai sharing this favorite food at the time. He was later added to the game in November 2017.
In the French version, the Title was called "Astro".
The Final Fantasy XIV Collaboration/Kula Revolving Sushi Bar Yo-kai Watch: Wibble Wobble magnets special events spelled his name with standard spelling when he was was localized worldwide, much like the other mascots.
In the Japanese version, Usapyon's verbal tic "dani" doesn't reflect his animal species like Jibanyan's "nyan" or where he's from like Komasan's "zura" and "monge!".
In addition to this, there's a slight joke about this as Sgt. Burly recognizes his cry for help as being from him since of the "weird speech" of "dani."
Also, in EP146, when Phonius is telling Hailey Anne the witness' information on what "Usapyon" looks like, one of the pieces of info is "Says the mysterious 'dani.'"
Usapyon's color scheme of the Yo-kai Pad is different depending on the media form. In the games, Usapyon has a white-and-blue Yo-kai Pad, whereas his Yo-kai Pad in the anime has an entirely blue color scheme.
The acronym in his name has been made lowercase to avoid mispronunciation.
Usapyon was planned back in spring 2014, when the franchise was beginning to rise in popularity and went through many different designs, starting out as a yellow floppy-eared rabbit before evolving into a blue kangaroo-like creature and eventually an otter with a spacesuit for his final appearance.
In the European-language versions of the manga and anime series, Usapyon tends to integrate English words into his sentences, alluding to his origin.
Usapyon's pronunciation of the name is different between languages. In Japanese, Korean, European and Southeast languages, it is pronounced "ooh-sap-yon" while in the English dub of Usapyon Is Here!, it is pronounced "ooh-say-pee-on". In the games his name is pronounced as "ooh-sap-yon" though in Yo-kai Watch 3 Hailey Anne still pronounces his name as "ooh-say-pee-yon" in cutscenes. This makes his English name the first to be pronounced in many different ways, unlike Jibanyan, Komasan and Komajiro.
Usapyon's country accent in the dub may be a reference to the fact that main space stations are located in Southern United States, where dialect like that is common.
In the games, Usapyon's Soultimate is called "Bunny Beam"; however, in Yo-kai Watch: Wibble Wobble, Usapyon's Soultimate is called "Supersizzler". Usapyon's special in Final Fantasy XIV Online is also named "Bunny Beam" which is the first appearance of the name.
In the games, Usapyon is voiced by Melissa Hutchinson. In the English dub of the anime, Usapyon is voiced by Katie Leigh.
Usapyon is the second Yo-kai to have interchangeable Soultimate moves. The first Yo-kai to do this is Jibanyan.
In the manga, Usapyon is a lot more cheery (probably as a gag) after his Invader Mode is over.
Usapyon is the first Mascot Yo-kai to have it's Japanese voice actress recasted. In the original Yo-kai Watch anime series, and all the games up to Yo-kai Watch Busters 2, he was voiced by Kotori Shigemoto. Due to Shigemoto's retirement from performing arts in March 2019, Usapyon was instead voiced by Hana Satou in Yo-kai Watch 4 and Yo-kai Watch!.
Usapyon's "random" nicknames in Yo-kai Watch 3 are: Champyon, Chibi, Hopson and Danny
Danny refers to his name as an otter and Chibi references his Japanese name as an otter