Koko, a six-year-old girl, constantly wears a distinctive penguin coat given by her father before his disappearance; its sleeves are sewn together to resemble flippers. Wearing this coat triggers her accidental transportation to a realm inhabited by goblins. These goblins revere a legend about a brave, flightless bird destined to overthrow evil. Mistaking Koko for this prophesied penguin savior, they believe she alone can save them from the demonic forces under the Emperor of Darkness. Initially unaware of the legend and her perceived heroic role, Koko adapts to her extraordinary situation. She befriends Chaley, a goblin, and Zammie, a fallen angel. Together, they confront the overwhelming demonic threat, despite Koko's initial uncertainty about how a young child could oppose an army of demons. Her motivation stems from a fierce desire to aid her new friends and protect their realm, summoning courage beyond her years. The coat remains a potent symbol throughout her journey, embodying her connection to her lost father and her unexpected identity as a hero.