The episode begins with the explanation of the story of the hero who long ago fought against an Archfiend who was making the people suffer. The hero and his partners defeated the Demon, and then, all the monster were released from the evil spell and were left to live in peace on Dermline Island, a place isolated from all humans.
In the present time, Dai is the only human on Dermline Island. The old wizard monster Brass adopted him, when he was just a little baby. Dai trains magic with Brass, but the boy has no talent for it. Brass wants that Dai turns into a magic user to help people, but the young boy want to be a hero and obtain the Crown of Heroes.
One day, when Dai was sat on rock near the sea, he saw the Fake Heroes, a group of thieves that act like real heroes, sailing to Dermline Island. The little boy greeted the thieves, thinking they are real heroes. Zurbon, the only woman of the group asked to Dai if he could show them the island, because they wanted to protect it. After Dai gathers all the monsters but Brass and Gome, Dai's best friend and very rare slime, Zurbon ask him if there is a pretty slime on the island, referring to Gome. After Dai goes after Gome, Brass arrives and discover the real identity of the Fake Heroes.
When Dai comes back with Gome, Derolin, the leader of thieves, is attacking the innocent monsters from Dermline Island, with the help of the other members. Dai is defeated by Zurbon's Boom, and Gome is kidnapped. Enraged, Dai decided to rescue Gome, but he can't get to the Kingdom of Romos, the place that the fake heroes went to. So Brass gives him a bunch of Magic Cylinders, tubes that can carry monsters inside, and a magic ball that the Dark Lord gave Brass a long time ago, that should be thrown up when the user is in danger. Dai catch some monster, like the Antnibbler and the Chimaera, and depart to Romos.
The Fake Heroes, after lying to the king saying they were attacked by the monsters, offered him Gome in exchange for the Crown of Hero, that the king accepted to give them at the royal feast. When Zurbon is buying clothes to use in the feast, Dai uses a monster to make her sleep and kidnap her. After waking up, Zurbon finds herself tied to a pole, inside a abandoned house, full of slimes. Dai ask her where Gome is, but she refuses to talk. Then, Dai jump at Zurbon and take off her boots, hat and trousers. Dai releases the Antnibbler and order it to tickle Zurbon's bare feet. Zurbon gives ups and tells him that Gome is in the castle and her friends weakness, Masopho is afraid of weird dances and Herohero likes all types of money.
Dai infiltrates the castle and release all the monster making a fuss. Masopho and Herohero are defeated when they tried to stop Dai to flee with Gome. Meanwhile, Zurbon seduce the slimes that were taking care of her, capture then and goes to the castle to help her friends. Since Derolin has no weakness, Dai fights with him alone, with no monster to help. The little hero is able to stole Derolin's swords using a candlestick, but Zurbon arrives at castle, when the leader of the thieves was about to surrender, with the slimes as hostages. When Dai's about to be killed by Derolin, he throws his magic ball up, creating a blinding light. When everyone in the castle is blinded, the slimes merge into king slime and jump onto Zurbon. Dai manages to capture Derolin inside a Magic Cylinder. After seeing that fight, the King of Romos realizes that Derolin is not a hero, but Dai is. So the king gives The little boy the Crown of Champions. The episode ends with Brass saying that he hid the Crown of Champions since Dai's destiny is to be a magician
The narration of the Hero's party against the Dark Lord does not reuse Baramos' design anymore.
Dai wears arm and leg wraps from three months later while in the manga he started wearing flip-flops and had bare arms. And when he departs from the island, he has legwraps and an armlet over bandages on his right arm due to his injuries from the Fake Heroes.
Did not show a flashback of the hero defeating a Dark Lord looking like Baramos
Added Masopho's line about Zulbon probably doing her make-up
Replaced Masopho's weakness against mud mannequins with one against treefaces. Herohero and Masopho are named on the weankess list in episode, while the manga did not reveal thier names before this episode aired.
Dai now simply uses a wooden sword and disarmed Derolin with a candlestick instead of using and breaking a Romos sword he picked on the ground.