Bernie is a Mii from the Switch.
Bernie originally appeared as the default Mii for the Lax Soldier role in Miitopia (Switch, Demo). He later appeared in the full game of Miitopia (Switch). Once the player replaces him with a Mii of their choice, Bernie 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_Soldier01.charinfo.
His Mii name in his Mii data file is ゆるいへいし, which translates to "loose", referring to his role's attitude. His height is set to 21 and his build is set to 74. His Mii ID is as follows: 02 53 BA DB 16 B0 44 49 8F 3B E3 9C 29 90 42 84
His Mii data file does not contain any unused Mii data.
Bernie's role in Miitopia (the Lax Soldier) 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 there are still visible differences between Bernie and the promo art Mii.
The names of the default Miis in Miitopia Switch often vary drastically depending on region. Bernie's name on the Mii Library is going off of the US English version, for consistency. A chart containing all of Bernie's names is located at the bottom of this page.
Bernie unfortunately does not appear in any promo art. In the demo version of Miitopia (Switch), he also never actually appears in the story, and only appears once in the casting screen. 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)