Everyone in Tempest is busy preparing for the festival to celebrate the country's opening. Rimuru visits Mjöllmile to share ideas on forms of entertainment that will keep people coming back for more.

Responding to Rimuru's concerns about monsters in the forest harming humans, Vesta and Kaijin reveal a new invention they hope will keep the road to Tempest safe. Also, Rimuru assigns a new task to Geld.

The spread of false information causes the Temple Knights to assemble, endangering Diablo's plan to conquer Falmuth. Meanwhile, Rimuru learns that Hinata is on her way to Tempest.

Demon Lord Ramiris tries to argue her way into moving to Tempest, where there's great food, hot springs, and ample entertainment. Rimuru happens to walk into the argument and comes up with a way to make use of Ramiris's skills.

The Seven Days Clergy have been purged, and the battle is over. Rimuru and Hinata hold a meeting to discuss future relations between their two nations, and the masterminds behind the whole conflict, the Eastern merchants, are revealed.

Rimuru is building a dungeon in preparation for the upcoming festival. It will feature treasure chests containing weapons made by Kurobe, and Veldora will inhabit the deepest floor as the final boss. Then Milim suddenly shows up with a suggestion...

Expecting visitors from all races to come calling after learning that Rimuru now controls the entire Great Forest of Jura, Rimuru decides to hold a festival to introduce himself and Tempest to the world, with the goal of attracting new citizens.

After meeting with the kings of various nations, Rimuru heads to Engrassia to invite his former students to the festival. The kids are thrilled to go back with him to Tempest, but then the hero Masayuki arrives as well...

After learning about an elf slave trade, Rimuru had Soei investigate, but it turns out the slave traders have already been shut down by Masayuki, the Lightspeed Hero. Word is now spreading that the Hero is headed to Tempest to slay a Demon Lord...

The night before the Opening Festival, Rimuru throws a lavish banquet for all the nobles and royalty visiting Tempest. When the party is in full swing, Empress Elmesia of the Sorcerous Dynasty of Thalion arrives, throwing everyone into chaos.

Phobio can't restrain his anger toward Milim. He finds himself faced with Footman and Tear, two masked members of the Moderate Harlequin Alliance, who suggest that he become a Demon Lord to take revenge on Milim. They tell him that he can accomplish this using the power of Charybdis. Meanwhile, the Jura Tempest Federation sends Youm out on a journey to make the world believe he was the champion who defeated the Orc Lord.

It's day one of the festival, and Rimuru finally gets to see all of his friends' performances and presentations. As he's enojying the festivities, he's summoned by Luminus...

As prominent figures from several nations assemble in Tempest for a meeting, Laplace and his companions formulate a plan centered around Clayman. Then someone familiar joins the discussion...

Rimuru announces his plan to back Youm as the new king of Falmuth. After hearing this, Gazel tests Youm to see if he has what it takes to be a ruler, and Youm answers with full sincerity. Erald also takes a liking to Rimuru after hearing him say he just wants to create a world where everyone can prosper and smile. Thus Rimuru and his allies look ahead to the battle against their new enemy, Clayman.

Yuuki is saddened by the death of Clayman, and Luminus is saddened by the death of Roy. Steeped in sadness, and having lost their friends, they seek their next move against Rimuru, who has grown in power and become a true Demon Lord.

A war council led by Hinata is held in the Holy Empire of Lubelius. Moments after Hinata declares her intent to meet Rimuru and talk to him, she receives a hostile message from Rimuru.

Numerous representatives from across the Great Forest of Jura have assembled in Tempest to congratulate Rimuru on his appointment to Demon Lord. Shuna requests holding a three-day audience to meet with them.

The Demon Lord Carrion has sent one of his Three Beastketeers, Phobio, on a raid of Rimuru's city. However, Phobio is quickly defeated when Milim meets his attack with her own. Rimuru and his subordinates then ask Phobio why he has come to their town.

The threat of Charybdis has gone. That night, Rimuru has a dream in which he sees Shizu teaching children at her school in the Kingdom of Ingrassia—a dream showing Shizu's lingering regret. To see her wishes through, Rimuru leaves the Jura Tempest Federation and heads for the capital of the Kingdom of Ingrassia. His first goal is to meet with the Grandmaster of the Guild, Yuuki Kagurazaka, who happens to be a Summon and a former student of Shizu's.

Rimuru tries to think of a way to save the children of Freedom Academy who are fated to die. The idea he comes up with is to have superior spirits inhabit each of them, as Shizu had, so their lives won't end prematurely. Determined to whatever it takes to save them, Rimuru leads the children to the Dwelling of Spirits, where superior spirits can be found. But as they make their way further inside, a Golem made of magisteel and controlled by the fairy Ramiris stands in their path.

A new force has suddenly risen to power in the Great Forest of Jura, and its leader, Clayman, proposes that the Demon Lords hold Walpurgis with the goal of sanctioning the slime who deceived him. Rimuru also begins to prepare for a battle with Clayman, but observing the enemy army's movements reveals that Clayman's target is not Tempest, but Eurazania. Clayman's army will arrive in Eurazania within two days. Can Rimuru's forces get there in time?

Gazel and Elmesia pledge to assist Rimuru with Tempest's lack of funding. Elmesia then proposes an alliance, but she's concerned about the danger Diablo poses.

Rimuru's dungeon is finally revealed, and his new ally Masayuki is among its first challengers. Later, after the festival is over, Rimuru's biggest job still awaits.

Rimuru pays the merchants with the gold coins he's procured. The merchants try to garner futher favor, but Rimuru ceases trading with them. Rimuru then gathers his allies and calls for action again the eastern merchants who are operating in secret.

Mikami Satoru, a businessman, is stabbed by a criminal on the street and killed. When he regains consciousness in the darkness, he finds that he's been reincarnated as a slime! With nothing better to do, he spends his time devouring all the rare herbs and precious ores he comes across. As he does, he encounters the Storm Dragon Veldora, who was sealed in this cave 300 years ago by a hero's "Unlimited Imprisonment" skill. He's frightened at first, but as they talk, he becomes friends with the long-isolated Veldora.