Monster Association Arc

The Monster Association Arc is the fifteenth arc of the series, and the sixth arc of the Human Monster Saga.

Plot
The shinobi duo Gale Wind and Hellfire Flame offer Speed-o'-Sound Sonic a monster cell and invite him to join them in their conquest to kill Flashy Flash.

The Monster Association sends a messenger to relay a message to the Hero Association. At the Monster Association base, Gyoro Gyoro and Orochi establish their dominance over the monsters.