The Demon Lord Leon Cromwell summoned Shizu out of Tokyo as it burned during in the air raids, then forced the high-ranked spirit Ifrit to possess her. After taking over Shizu's body, Ifrit begins to rampage.

When Shizu was still with Demon Lord Leon, it was a Hero who rescued her. That Hero was Shizu's inspiration to help as many people as she could for many years. She even worked as a teacher for children who'd come from other worlds. And now, as her time comes to an end, Shizu asks Rimuru for one last favor...

Rimuru and the Goblins' village is developing nicely. The Dwarves are building all kinds of houses and furniture, and the local Goblin Lords have appointed Rigurd as the Goblin King. As Rimuru watches everything come together, he decides to return to the cave and test the skills he received from Shizu. While there, he receives a request for help from Ranga through Thought Communication, and he rushes back to find his friends facing six Ogres. One of them orders Rimuru to "reveal his true identity." What is going on in the Great Forest of Jura?

Six Ogres are all that remain of their clan after an attack by an Orc army. They say that the Orcs were traveling with a mysterious majin who wore plate mail and a clown mask. Rimuru proposes that the Ogres join his ranks, and they accept on the condition that they will get to take down the one leading the Orcs, so Rimuru gives all six of them names. Meanwhile, the Orcs begin to invade the marshlands surrounding Lake Siss that are inhabited by the Lizardmen. So the Lizardman chieftan gives his son, Gabiru, an order...

Rimuru's village has gained Benimaru and the other five Ogres as its newest allies. Soon after, the Lizardman Gabiru visits the village, having heard rumors about it. Gabiru has been visiting Goblin villages throughout the Great Forest of Jura to enlist their aid in fighting off the Orc army. When he faces Ranga with an attitude of provocation, Ranga tells him that if he can defeat Gobta, they'll hear what he has to say...

The Orc army, led by the Orc Lord, continues its conquest throughout the Great Forest of Jura. The crisis has spurred Treyni of the Dryads, the caretakers of the forest, to take action. She has had her eye on Rimuru after noticing his rise to prominence in the forest, and she wants Rimuru to defeat the Orc Lord.