Rimuru was originally a 37-year-old office worker named Satoru Mikami living in Japan. After losing his life protecting a junior from a random attacker, he is reincarnated into another world and begins a new life as a Unique Slime. Upon reincarnation, he acquired the unique skills "Predator" and "Great Sage" and met the Storm Dragon Veldora in a cave. He and Veldora acknowledged each other, and as proof of their friendship, he was given the name "Rimuru Tempest." At the point of reaching the Goblin village, Rimuru is not yet a Demon Lord or a head of state, but simply a slime who "cannot leave people in trouble alone." However, within him live the calm judgment he cultivated as a working adult in his previous life and values that cherish trust-based relationships with others. Though he looks like a small blue slime, his body is composed of high-purity magicules, hiding potential far beyond that of a typical slime. His methods of attack are not limited to physical strikes; he can use "Predator" to consume targets, analyzing and acquiring their abilities and materials. Furthermore, "Great Sage" constantly analyzes the situation and advises on the best course of action, allowing him to respond flexibly to unknown events. His personality is gentle and friendly, treating even those he meets for the first time without discrimination. On the other hand, he is merciless toward those who harm his friends and is prepared to fight if he deems it necessary. However, during this period, he is still strongly conscious of the weight of "taking a life" and his stance of avoiding conflict as much as possible is prominent. The encounter with the Goblins is a major turning point that changes Rimuru's life. Unable to abandon them as they cowered before the threat of the Direwolves, he accepted their request and ended up naming every villager. Naming monsters was a dangerous act that consumed vast amounts of magicules, but he prioritized the feeling of "not wanting to abandon them now that they are comrades." Triggered by this event, the Goblins evolved, and a new village-building effort centered around Rigurd began. At this time, Rimuru's dream is nothing more than a vague ideal of "creating a country where everyone can live and laugh in peace." However, through interaction with the Goblins and reconciliation with the Direwolves, he gradually turns the future of multi-species coexistence into a realistic goal. Although his combat ability is already high, he has a cautious side toward unknown enemies due to lack of experience. Therefore, rather than charging ahead alone, he places importance on listening to his companions' opinions and acting while assessing the situation. This flexibility and inclusiveness are the origins of his qualities as a "Chancellor" who will later attract numerous monsters and people. Rimuru in the Goblin Village Arc is not the strongest being, but a protagonist in the middle of growth who increases his allies using "kindness," "wisdom," and "action" as weapons to slowly carve out the future. The accumulation of those steps is the beginning of everything that leads to the later founding of the Monster Federation (Tempest).

Gobta is a young Goblin named by Rimuru. He is particularly active within the Goblin village and has a bright, friendly personality. He is usually a mood-maker who makes his friends laugh with lighthearted jokes, but he has the courage to jump out first when his comrades are in danger. He steadily grows stronger through training, and in battle, he baffles enemies with quick movements and flexible thinking. He is a lovable, growing character who respects Rimuru from the bottom of his heart and values the bonds with his friends above all else.

Rigurd is the chief of the Goblin village and a reliable leader who evolved after being named by Rimuru. He possesses calm judgment and a broad perspective, acting with the safety and livelihood of the villagers as his top priority. He has a polite and sincere personality, and his loyalty to Rimuru is extremely deep. In battle, he uses his wealth of experience to lead calmly, and he also puts effort into the development of the village and interaction with other species. Combining strictness and kindness, he is a figure deeply trusted by everyone in the village.

Ranga is the son of the Direwolf chief. After his father's death, he swore loyalty to Rimuru and evolved into a Tempest Wolf after being named. He is usually calm and taciturn, but he places absolute trust in Rimuru and follows orders faithfully. He also has a side that cares for his comrades, rushing to protect them first if danger approaches. He excels at scouting and movement using his excellent sense of smell and agile legs, and boasts high combat ability. Due to his dignified appearance and loyal personality, he is beloved by his companions as a reliable presence in Tempest.