That Time I Got Reincarnated as a Slime Season 4

With the Founding Ceremony a resounding success, Tempest takes a new step toward realizing a Monster-and-Man Cooperative Alliance. As Rimuru inspects the town, he spots a group of adventurers aiming to conquer the Dungeon getting into a scuffle with Benimaru and the security squad.

Thanks to Masayuki's idea to open up the rest area and the promotional effect of the high prize money, the revitalization of the dungeon was a massive success! Rimuru breathed a sigh of relief as operations got back on track, but now a party called Team Green Fury-a group of about 100 people-has appeared to conquer the dungeon.

To defeat Team Green Fury, Rimuru and his companions obtained temporary avatars for the dungeon. However, their teamwork was poor, and they ended up losing even to low-level challengers. So the group decided to strengthen their equipment and undergo special training to improve their coordination. And so, the decisive battle against Team Green Fury begins on the 49th floor of the dungeon.

Even after defeating Team Green Fury, Rimuru and his companions continue their special training in the dungeon, becoming figures feared by adventurers as the Dungeon Dominators. Meanwhile, the publicity campaign featuring Masayuki as its poster boy was a huge success, and the dungeon is becoming increasingly popular.

Following a summons from the Council of the West, Rimuru and his companions arrive in the Kingdom of Engrassia. Upon hearing from Hinata, who has already attended the council meeting, that Tempest admission to the council is a certainty, Rimuru's heart swells with anticipation.

Realizing through Raphael's words that someone's schemes were at play, Rimuru lifts the mental interference cast on the councilors and begins to win them over. However, just then, Prince Elrick of the Kingdom of Engrassia appears, declaring his intent to defeat Demon Lord Rimuru and inciting his subordinate, Reiner, and the adventurer Guy to attack.

The assassination attempt on Prince Elrick, which was planned to take advantage of the chaos in the assembly, is foiled by Rimuru's actions, and the Council concludes with Tempest joining the Council. Upon returning to the Tempest, Rimuru and the others begin interrogating Glenda, the culprit of the assassination attempt, but she is unable to answer due to her soul being bound by a curse.

Yuuki is being controlled by Maribel. After receiving information from Glenda, who has joined their ranks, Rimuru decides to avoid contact with the Free Union. However, the date of the joint ruin expedition with the Free Union, which has already been scheduled, is fast approaching. To guard against enemy traps, Rimuru begins making thorough preparations.

Rimuru and his expedition team have arrived at Amrita, the ancient ruins located beneath the castle of Clayman, the Demon Lord they once fought. From analyzing magical formula to examining ancient murals, the group proceeds with their expedition, driven by their curiosity. Meanwhile, on the surface, Maribel is closing in on them.

Maribel's unique skill, "Greed", has no effect on Rimuru, who has awakened as Demon Lord, and the gap in their power is clear. Having blocked all of Maribel's attacks, Rimuru attempts to defeat her, but Yuuki-who has been imbued with the power of "Greed"-steps in to block his path.

Facing the Chaos Dragon, a friend she had once sealed away herself. Milim finds herself unable to fight. To prevent her from having to kill her precious friend, to avoid such a tragic outcome... Rimuru devises a plan to protect the soul of the Elemental Dragon that remains within the Chaos Dragon. Thanks to Yuuki defeating Maribel, Rimuru and the others successfully carry out their plan.

With Maribel's rule over, Tempest becomes the largest faction within the Council of the West. Rimuru declares that, in order to foster future relations with human society, he will transform Tempest into a nation governed by the law. After touring various regions, Rimuru expresses his hope that everyone would come together and thrive, with Tempest at the center.

Rimuru finally begins working in earnest on creating the vessels requested by Diablo. However, due to the staggering number of vessels required, the staff shortage in his lab had become severe. Just then, a certain Demon Lord comes to see Rimuru.

Diablo has left Rimuru and arrived in the Demon Realm. He visits three demons he has known for a long time to entrust them with handling the miscellaneous affairs of the Federation.

With the addition of new allies, Tempest begins its journey as a nation governed by law. Meanwhile, while Rimuru and his companions are busy with this, in El Dorado, Laplace and his group, disguised as merchants from the East, are making contact with the Demon Lord Leon.

Rimuru and his group arrive in Lubelius for the musical exchange conceived by the Demon Lord Luminus. That night, after being warmly welcomed, Rimuru is invited by Luminus to discuss a certain topic.

Demon Lord Leon, searching for Chloe, asks Elmesia of the Sorcerous Dynasty of Thalion for her help and sets out for Lubelius. However, the Granville army is already preparing to invade the city.

The Western nations are thrown into chaos by the demonic forces advancing from the north. As the forces approach the Kingdom of Engrassia, Testarossa, who had been dispatched to the Council on Rimuru's orders, is already there.