Plot
Following their desertion from Clayman's army, an Ogre and his fellow mercenaries are attacked by Clayman's soldiers, whose leader Yamza severely injures the Ogre. He is found by the people of the Kingdom of Raja and is given the name "Hiiro" by its queen Towa to recover from his injuries. Ten days later, Hiiro escapes Raja to return to the Ogre Village, only to find it destroyed by the Orcs. Wanting vengeance against the Orcs, Hiiro returns to Raja four days later and swears loyalty to Towa.
Rimuru, who recently defeated Clayman and has been recognized by other Demon Lords as one of their own, is informed by Souei of an attack toward Geld and his fellow Orcs. The Orcs are fighting against Hiiro and his two Raja subordinates, during which Geld learns that Hiiro seeks revenge against his race, so he drops his weapons and accepts his fate of being killed by him. However, Benimaru saves Geld and pacifies Hiiro, who actually is his childhood friend. Hiiro reunites with Benimaru, Shion, Shuna, Hakuro, Souei, and Kurobe, and reconciles with Geld after learning that the Orcs are no longer their enemies and that the one manipulating them is long dead. During a feast hosted by Rimuru, Hiiro reveals that he had arrived at the Jura Tempest Federation as Raja's messenger to ask permission to cultivate a part of the Great Jura Forest to serve as a food source for the kingdom. He informs that Towa is suffering from Curse Poison, the effect of using the power of her tiara to purify a lake filled with toxins from the country's gold mines. Milim Nava then joins in on the meeting, unhappy that she wasn't invited. Agreeing to help, Rimuru decides to visit the kingdom.
Rimuru, Benimaru, Shion, Shuna, and Ranga arrive at Raja. After analyzing her condition, Rimuru gives Towa honey from Tempest to restore part of her health. At the lake, Rimuru reveals to Towa that the toxins are not from mines, as he then splits the lake into two to reveal a hidden structure with an old magic circle that produces the toxin and destroys it. These events have angered Lacua, the merchant behind the poisoning, and schemes to create another disaster to earn praise from the Primordial Demon Violet. The lake is poisoned again, so Towa uses her tiara to purify it, resulting in her health deteriorating. A neighboring country takes advantage of her worsening condition to attack Raja and seize the gold that the kingdom mined. Having learned of the news about the encroaching enemy, Rimuru mobilizes his allies, while Diablo heads out to meet with Violet, who created the tiara and the magic circle at the lake.
Hiiro is tricked by Lacua to ingest a Curse Orb, being told that it is for transferring Towa's soul to his healthy body, and is fed by him with memories of his village being destroyed to fuel his transformation. Rimuru chases after Lacua, while Benimaru fights Hiiro and Shuna protects Towa. Meanwhile, Diablo confronts Violet, who reveals that she had given the tiara to a previous queen of Raja as part of a game with Raja's royal line in which if the possessor is fully inflicted by the Curse Poison, then she can take over the body and be physically reborn. After failing to defeat him, Violet agrees to Diablo's terms of leaving Raja alone while also voiding the contract with Towa and her line after learning that Lacua interfered with her game against her wishes instead of observing only. She cuts ties with Lacua for ruining her fun. Chikuan, Towa's doctor, is revealed to be in allegiance with Lacua, but he is killed by Ranga. Rimuru eventually defeats Lacua, who blows himself up to destroy everything around him. However, the explosion is contained by Rimuru. Hiiro removes the orb from his body and destroys it.
Towa uses the full power of the tiara to revive Hiiro from the Curse Orb, causing her body to be covered by the Curse Poison and vanish. However, Violet revives Towa after voiding the game as an apology for her subordinate's actions. While celebrating, Rimuru offers the kingdom's ministers help in rebuilding Raja in exchange for Tempest buying their iron ore. Rimuru returns to Tempest, finds it partially destroyed after Veldora and Milim played together, and punishes them before collapsing from exhaustion.
