Mario and co first come to Mount Brrr while searching for Princess Peach, who has been taken to Bowser's Villa by Bowser Jr. and his paper counterpart. Entering from Gloomy Woods thanks to the services of Flutter, the trio try navigating the mountainside in order to find their to the top. However, King Bob-omb and his troops have set up a base on top of the mountain, and block the group's path with paper landscape items too high to jump over. This gives the trio the opportunity to learn the Trio Drill move to go underground and bypass obstacles, as well as climb the dirt walls covering the mountain cliffs.
After a bit more trekking up the mountainside, the trio come across a Toad Village. Rescuing more paper Toads in missions there, they end up encountering the Bowser Jr. duo outside the villa, where they engage in a papercraft boss battle with Papercraft Bowser Jr.. However, Princess Peach gets taken back to Bowser's Castle by the two Bowser Jrs., and the trio give chase, finding a mysterious Bowser emblem on the way.
The trio return to Mount Brrr a bit later in their adventure, after seeing Bowser's Castle take to the sky and become Neo Bowser Castle. Noticing the castle is now floating above the mountain, they again scale the mountainside in an attempt to find a way up.
This time however, they take a different route. This side of the mountain has various clouds and wooden structures littered about, as well as an ominous metal door with a Bowser symbol on it. After opening this door and taking the elevator, they end up at the summit, where King Bob-omb lies in wait. One timed boss battle later, and Toadette tells them to use the Paper Toads they've collected to form a bridge up to Neo Bowser Castle.
Names in other languages