Years after the meddling monkey Specter was first stopped, a young boy named Hikaru is left watching over the Professor's laboratory alongside his cousin and the Professor's granddaughter. A simple errand goes wrong when a batch of mind-controlling Monkey Helmets is accidentally scattered, and Specter seizes one to once again raise an army of monkeys bent on ruling the world. Armed with an arsenal of quirky gadgets and joined by a friendly baby monkey named Pipotchi, Hikaru sets off across a variety of worlds to recapture the escaped monkeys and foil Specter's plan.