Sonny is a Mii from the Switch.
Sonny originally appeared as the default Mii for the Besmirched Noble's Son role in the files of Miitopia (Switch, Demo), but unused within the demo itself. He later appeared in the full game of Miitopia (Switch). Once the player replaces him with a Mii of their choice, Sonny would never appear again, unless that Mii is deleted. His Mii data file can be found in \cmn\storedata\npc_default_mii.sarc and is named Castle00_NobleKid00.charinfo.
His Mii name in his Mii data file is おちぶれk. His height is set to 86 and his build is set to 81. His Mii ID is as follows: 87 71 5A D8 9A A5 43 F5 8C F5 F0 6D 60 E2 D7 89
His Mii data file does not contain any unused Mii data.
Sonny's role in Miitopia (the Besmirched Noble's Son) is described as so:
He seems to bear resemblance to a Mii featured in Miitopia (3DS) promo art, as it seems a handful of the Miitopia Switch default Miis were based around Miis that appeared in promo art for the original game, but it's unconfirmed if Sonny and the promo art Mii are meant to be the same character.
The names of the default Miis in Miitopia Switch often vary drastically depending on region. Sonny's name on the Mii Library is going off of the US English version, for consistency. A chart containing all of Sonny's names is located at the bottom of this page.
Sonny unfortunately does not appear in any promo art. Below is a screenshot of him in-game as his role in Miitopia.
This Mii originally appeared on the Switch!
Here's how to recreate them on the Switch:
Names in other languages
Source: Miitopia (Switch, Demo)