Mario & Luigi: Bowser's Inside Story

Mario & Luigi: Bowser's Inside Story, released in Japan as Mario & Luigi RPG 3!!! (マリオ&ルイージRPG3!!!), is a role-playing game released for the Nintendo DS in 2009. Its previous installments are Mario and Luigi: Partners in Time and Mario and Luigi: Superstar Saga. It was first revealed at an October 2, 2008 press conference by Nintendo. As a part of the Mario & Luigi series, the game includes new features such as mini-games and the ability to play as Bowser and use his own unique battle system, which allows players to hold the DS sideways and use the touchscreen and microphone to perform special moves.

A mysterious plague called "The Blorbs" is taking over the Mushroom Kingdom. The unknown virus causes the Toads to inflate to many times their normal size and roll around uncontrollably. Humans like Mario, Luigi, and Princess Peach are not affected by the Blorbs disease. A council including the Mario brothers is called to discuss what can be done about the infectious virus. At this time, Bowser enters Peach's castle and tries to kidnap her by force, but Mario fights Bowser to protect the princess.

After his inevitable defeat, Bowser wakes up in a mystic forest, where a mysterious figure offers a Lucky Mushroom to him. Upon eating the mushroom, he unknowingly gains the ability to inhale objects and minimize people into his stomach, and the mysterious figure is revealed as Fawful, a villain from previous installments in the series. Fawful brain-washes Bowser and sends him to Peach's castle, where he swallows all the Mushroom Kingdom council members; Fawful then takes over Mushroom Castle.

When Bowser awakens, he proceeds to chase Fawful in an attempt to reclaim his castle. Meanwhile, Mario and Luigi must work alongside Bowser from within his body in order for them to find a way out and defeat Fawful.