The Promise to Toad
From the Super Mario Wiki, the Mario encyclopedia
The Promise to Toad (also referred to as Heroes Episode 5 and Heroes 5) is the fifth Heroes episode in the Story Mode of the Nintendo 3DS version of Mario & Sonic at the London 2012 Olympic Games. The episode is unlocked after completing To the Ruins!, and unlocks The Grand Showdown once it is completed. This episode's completion is required to unlock the Story Mode Cleared badge.
Sonic, Tails and Omega arrive outside Big Ben, and Omega warns them that the Phantasmal Fog levels there are dangerous. Mario, Luigi and Toad arrive, also noting the thickness of the fog. Omega says that his circuits may be damaged with prolonged exposure, and Toad also says that he is now struggling to breathe. A group of Fog Imposters of Mario, Luigi, Sonic and Tails arrive, which Omega says are more powerful than the ones faced before, and the group challenge them to an Olympic Event.
The group defeat the Fog Imposters, causing them to disappear once again and the fog to thin. Toad initially feels better and tries to carry on, but instead ends up collapsing from exhaustion. The group suggests that he heads back to Main Stadium for his own safety and agrees to do so after resting for a while first. Toad passes the walkie-talkie on to Tails, and Omega says that he will stay with Toad and return to the Main Stadium as well to prevent damage to his circuitry. The rest of the group head on to Big Ben.