Mario Golf: Super Rush is the 6th game in the Mario Golf series, released in June 2021 and developed by Camelot. While previous entries in the series has had Mii support, none have had actual Mii mascots. These two mascots of Mario Golf: Super Rush are commonly seen in most, if not, all promotional material relating to Miis for the game. However, they make no actual in-game appearance. Despite this, their Mii data files are in the game files, unused, letting us still access them despite their only official appearances being in trailers and images. Interestingly, these two Miis have a unique file extension: the .mii file extension. Previously only seen unofficially by third-party tools used to deal with Wii-format Mii data files, and given the .mii extension by fans, for the first time, it is now officially used for the charinfo format... but only for this game. Previous sources using this format gave the Mii data files an extension of either .bin (generic) or .charinfo (for example, in Miitopia (Switch)). This game using .mii implies that Nintendo has no standardized file extension for the charinfo format, leading to developers just using whatever extension they want.