Bowser's Fury

On a bright, clear day, Mario walks the path in front of Peach's Castle, near where he found the broken Clear Pipe at the start of the main campaign. Noticing small puddles of black goop, he follows them until he reaches a mass of black graffiti shaped like Shadow Mario's logo from Super Mario Sunshine. The graffiti spreads into a portal that Mario tumbles through, carrying him to a rain-lashed Lake Lapcat. Soon after landing, Mario encounters Bowser — now transformed into a larger, more powerful form known as Fury Bowser. Finding a Cat Shine nearby, Mario uses it to clear the goop from a lighthouse, and the resulting beam of light blinds Fury Bowser, who retreats into the Fury Sun at the center of Lake Lapcat as several islands rise from the water. With Bowser gone and the storm cleared, Mario finds a panicking Bowser Jr., who explains the cause of the transformation: showing a picture he painted of his father and then blackening it with his Magic Paintbrush, Bowser Jr. reveals that he was the one who corrupted Bowser. Realizing he and his father are both in trouble, he reluctantly asks Mario for help — making clear this wouldn't happen under normal circumstances — and Mario agrees, with Bowser Jr. joining him for the rest of the adventure.