That Time I Got Reincarnated As A Slime took isekai fans the world over by surprise, its humorous characters and more light-hearted tone making it stand out from other popular series like Sword Art Online or Overlord. The idea of a human taking on the form of the weakest monster and somehow becoming shockingly powerful it up the imaginations of anime viewers, making them tune in to the adventures of the peace-loving slime, Rimuru Tempest. The anime has since taken a darker turn, and Rimuru has learned the true burdens of leadership. Fortunately, he's not alone in his efforts to build a peaceful kingdom for monsters. He has several allies and good friends by his side. Originally one of Rimuru's enemies, Geld is the son of the Orc Lord Disaster who attacks Benimaru's ogre village and the marshlands where the lizardmen make their home. The Orc Lord Disaster, also named Geld, is a significant threat due to his unique skill Starved that allows him and his subordinates to devour anything within their reach.
He tries to eat Rimuru, but Rimuru consumes him instead with his own unique skill. In the aftermath, Rimuru is merciful toward Geld I's minions, earning himself the loyalty of his son. Hard-working and dedicated, Geld II is also a powerful fighter, going against opponents like the Otherworlder Shogo Taguchi and easily winning. Shizue Izawa is an adventurer summoned from World War II Japan by the Demon Lord Cromwell. Her experience in her war-torn nation leaves her badly burned upon being brought to her captor's unfamiliar world. It also gives her an affinity for fire. Cromwell summons the Flame Giant Ifrit, and it possesses her, saving her life, but also engraving a curse onto her heart. She spends years as a demon under the rule of Cromwell but is eventually rescued by a hero hunting the demon lord. The hero also gives Shizue a special anti-demon mask which she can use to contain the power of Ifrit. But it is only a temporary solution, and by the time Shizue appears in the anime, she is an old woman unable to fully contain her fire abilities. Rimuru absorbs Ifrit, but she dies anyway. Shizue asks Rimuru to consume her, allowing Rimuru to use a humanoid form later. The massacre of the ogre village may have been a tragedy, but to Rimuru, it brings an unexpected boon. A group of ogres arrives in Tempest, originally believing Rimuru to be the culprit behind their misfortune. They are soon proven wrong, and Rimuru helps them evolve from ogre to kijin.
The information he provides Rimuru is vital to the growth of Tempest as a nation.
The new arrivals have since earned many fans of their own, and they most certainly deserve it. As one of Rimuru's new subordinates, Souei leads the Shadow Squad of the Jura Tempest Federation. He's in charge of everything related to intelligence, and he's able to travel quickly from place to place. The information he provides Rimuru is vital to the growth of Tempest as a nation. He's deadly with his steel threads and his katanas can even shear into a person's soul. A former ogre just like Souei, Shion isn't a very good cook and has trouble deciphering her own handwriting. When she summons a massive ball of magic in her fight against Demon Lord Carrion's Beastketeer Suphia, she isn't able to properly wield it. However, she's still a fierce warrior that few can take on in combat. Her recent resurrection has only boosted her abilities, and she's very creative with the use of her new unique skill Cook. Rimuru may not trust her cooking abilities, but he's happy to have her by his side when he has to face other Demon Lords.
Ranga is one of Rimuru's very first subordinates. He is the leader of the Tempest Wolves, Direwolves that evolved after Rimuru named them. Ranga's father is also one of the opponents Rimuru kills, but Ranga doesn't begrudge him for that. Instead, he is proud to have such a powerful master, and his loyalty to Rimuru knows no bounds. He often stays in Rimuru's shadow, ready to serve Rimuru at a moment's notice. Princess Shuna doesn't often visit the battlefield. She is a great asset to Rimuru in the handling of diplomatic affairs and day-to-day matters in Tempest. But when Shuna is filled with righteous anger, she is effortlessly able to defeat the undead Adalman, tricking him into using holy magic and turning his own power against him. Her spell breaks the enchantment Clayman has over Adalman, leading the undead lord to change sides and ask to meet Rimuru as well.
A more recent addition to Rimuru's entourage, Diablo is summoned by Rimuru after Rimuru uses Meggido to ascend as a Demon Lord. He easily defeats Razen and evolves from Arch Demon to Demon Peer after Rimuru's Harvest Festival. He is extremely loyal to Rimuru, to the point of starting a rivalry with Shion over it. Fascinated with Rimuru and his power, he wishes to make his master's wishes come true at all costs. His appearance and behavior are a little reminiscent of Black Butler's Sebastian Michaelis. The Commander-in-Chief of Tempest's military forces, Shuna's brother Benimaru is able to defeat scores of opponents using his mastery over his fire abilities. A single Hell Flare obliterates the inferior version of Charybdis used by the Demon Lord Clayman's forces. His abilities don't lie only in physical attacks. Following Rimuru's Harvest Festival, he receives the unique skill Generalissimo, which allows him to sense the flow of power among his troops, predicting their chances of victory and giving them a bonus at the same time. The Demon Lord Milim is as powerful as she is fun-loving.
The two become friends and Rimuru agrees to help free Veldora from the spell keeping him captive.
She first visits Tempest out of boredom, and Rimuru manages to befriend her, welcoming her to Tempest. She considers him her only friend, her "bestie," and Rimuru is very fond of her as well. Even when all signs point that she has turned on them, Rimuru still has faith in her. He is furious when Clayman hits her during the Walpurgis meeting between the Demon Lords. But Clayman will certainly come to regret toying with Milim. She may sometimes act childishly, but she's capable of easily defeating the Demon Lord Carrion, and is acknowledged as one of the oldest and most powerful Demon Lords. The Storm Dragon Veldora is the first being Rimuru encounters after his reincarnation into his new world. The two become friends and Rimuru agrees to help free Veldora from the spell keeping him captive. The fourth True Dragon, Veldora is a being of such power that even while trapped, his presence prevents others from claiming the Jura Forest. Dreaded as a true calamity, Veldora has become even more powerful after Rimuru's Harvest Festival. He also possesses a form of soul bond with Rimuru, and he is given a humanoid body to inhabit by his friend.
Moon Breathing (月 (つき) (こ) (きゅう), Tsuki no kokyū?) is a Breathing Style derived from the Sun Breathing used by Upper Rank One, Kokushibō, who was one of the first Demon Slayers who utilized breathing techniques. The techique allows the user to create many "chaotic blades" when slashing that varies in length and size. It is known that Kokushibō continued to develop and add techniques to the Breathing Style over the centuries as an immortal Demon. At this point in the story, it is the only known Breathing Style to possess at least 20 different techniques, easily surpassing the other Breathing Styles. It has been revealed that, like all of the other original breathing styles, the Moon Breathing also branched out of the Sun Breathing. When its creator, Michikatsu Tsugikuni, attempted to learn the Sun Breathing from his twin brother, Yoriichi Tsugikuni, he discovered he was unable to master the breathing style and so was instead trained in an alternate Breathing Style. Yoriichi created it fit and cover his individual strengths and weaknesses, and Michikatsu then continued to train and develop this breathing until it eventually evolved into its own unique Breathing Style, which he named the Moon Breathing.
First Form: Dark Moon, Evening Palace (壹 (いち) (かた) (やみ) (づき) (よい) (みや), Ichi no kata: Yamidzuki - Yoi no Miya?) - Kokushibō draws his sword and slashes swiftly in a single motion; like with all Moon Breathing techniques, numerous chaotic blades originate from the slash. This technique resembles Iaijutsu. Second Form: Pearl Flower Moongazing (貳 (に) (かた) (しゅ) (か) (ろう) (げつ), Ni no kata: Shuka no Rōgetsu? ) - Kokushibō performs several slashes while sending a barrage of chaotic blades forward. Third Form: Loathsome Moon, Chains (參 (さん) (かた) (えん) (き) (づき) (つが), San no kata: Enkizuki - Tsugari?) - Kokushibō swings his sword rapidly in two gigantic crescents slashes, from which a storm of smaller crescents spread.