Season 1
Rimuru has saved the children he was teaching in the Kingdom of Engrassia, and his time as a teacher is nearly over. Then Yuuki, Grandmaster of the Free Union, asks him to get to the bottom of the race for the throne in the Kingdom of Coleus, which is located between Engrassia and the Holy Empire of Lubelius. So Rimuru infiltrates Coleus under the name "Satoru," and he finds a nation at the mercy of not only a battle for succession, but a web of schemes woven by demons and vampires!
01. To Coleus
Yuuki asks Rimuru to investigate the Kingdom of Coleus, where a battle for succession has pitted the kingdom's two princes against each other. Rimuru launches a covert operation to sneak into Coleus and find out what's driving this conflict.
02. Great Phantom Thief Satoru
Aslan visits Rimuru to thank him for saving his sister, Zenobia. They discuss her illness and Souther's behavior, and begin to suspect that the court physician, Gustav, is behind both. Rimuru dons yet another disguise to investigate further.
03. Purple and Roses
Rimuru confirms that it was Gustav who cursed Zenobia with illness. It turns out he and his accomplice, Carl, are Archdemons plotting to manifest their god using Zenobia as a vessel. Can Rimuru stop them before the Kingdom of Coleus is lost?