That Time I Got Reincarnated as a Slime, Vol. 1 by Fuse Summary

That Time I Got Reincarnated as a Slime, Vol. 1 follows Satoru Mikami, a 37-year-old Tokyo salaryman who is murdered while saving his friend. He awakens reincarnated as an overpowered slime in a fantasy world with unique abilities like "Predator". After befriending an imprisoned dragon named Veldora and gaining the name Rimuru Tempest, he becomes the leader of a goblin tribe and begins building a multi-species nation.

Fuse is a Japanese light novel author who originally serialized That Time I Got Reincarnated as a Slime online from 2013 to 2016 on the user-generated publishing website Shōsetsuka ni Narō. The series was later acquired by Micro Magazine and published officially starting in 2014, with twenty-two volumes released as of January 2025. Fuse's work has expanded into multiple manga adaptations, anime series, and films, establishing the TenSura franchise.

That Time I Got Reincarnated as a Slime, Vol. 1 appeals to fans of isekai fantasy, RPG-style world-building, and lighthearted adventure stories. Readers who enjoy protagonists focused on nation-building and diplomacy rather than pure combat will appreciate Rimuru's approach to helping goblins develop infrastructure and government. The story suits those seeking a blend of humor, overpowered protagonist tropes, and themes about leadership, community-building, and bridging differences between species.

That Time I Got Reincarnated as a Slime, Vol. 1 earns a "B" grade for its entertaining use of fantasy and isekai tropes. The novel successfully avoids making Rimuru too perfect by keeping him mostly as he was in his previous life, using contractor knowledge and RPG experience to navigate his new reality. Fuse builds a compelling world where the line between "monsters" and "humans" blurs, with effective emotional moments like Shizue's storyline balancing the lighter nation-building elements.

Satoru Mikami becomes Rimuru Tempest through a transformative friendship with Veldora, a powerful Storm Dragon sealed for 300 years. After Satoru reincarnates as a slime and befriends the lonely dragon, they exchange names following the world's custom—Veldora grants the name "Rimuru" while receiving the surname "Tempest" in return. This naming process grants Rimuru even greater strength and marks his evolution from an ordinary slime into a being capable of leading nations.

The Predator skill is Rimuru's signature ability that allows him to devour anything and mimic its appearance and skills. This powerful skill becomes central to Rimuru's growth throughout That Time I Got Reincarnated as a Slime, Vol. 1, enabling him to consume Veldora's prison to analyze the seal spell and later absorb Shizue Izawa to gain human form. Predator represents the core mechanic through which Rimuru acquires new abilities and evolves beyond typical slime limitations.

Veldora is a powerful Storm Dragon who has been sealed in a cave for 300 years after reducing a town to ashes. In That Time I Got Reincarnated as a Slime, Vol. 1, he becomes Rimuru's first friend in the new world, teaching him how to manage his powers and granting him the name "Rimuru". Veldora's disappearance after being consumed by Rimuru creates a power vacuum that establishes Rimuru as the leader of the Great Forest of Jura.

That Time I Got Reincarnated as a Slime, Vol. 1 explores transformation and unexpected potential, showing how Rimuru's journey from mundane human to powerful slime leader highlights growth in unexpected forms. The novel examines the artificial barriers between "monsters" and "humans," with Fuse demonstrating that behavior, not species, defines monstrosity—human adventurers act most monstrously while named monsters gain human-like intelligence and compassion. Additional themes include:

• Community-building
• Inherited responsibility through Shizue's legacy
• Using knowledge from one's past life to create positive change

That Time I Got Reincarnated as a Slime, Vol. 1 ends with Shizue Izawa's death and her final request for Rimuru to consume her and confront Demon Lord Leon Cromwell. This absorption grants Rimuru a human form and new abilities like Deviant and Control Flame, while symbolically inheriting Shizue's pain, regrets, and personal mission. The ending transitions from individual survival to ambitious nation-building, with Rimuru having united goblins and direwolves, secured dwarf allies, and laid the foundation for creating a multi-species community as a safe haven.

Shizue Izawa is a deceased human whose body Rimuru consumes, gaining the ability to manifest a human form based on her appearance. Her character provides That Time I Got Reincarnated as a Slime, Vol. 1 with emotional depth and establishes Rimuru's long-term mission beyond community-building. Shizue's final request—that Rimuru make Demon Lord Leon Cromwell "regret every moment"—gives Rimuru a personal quest and inherited purpose, transforming him from a reactive survivor into someone carrying another's pain and seeking justice.

Fuse writes That Time I Got Reincarnated as a Slime in first-person perspective, offering direct access to Rimuru's thoughts, reactions, and humorous commentary on fantasy world tropes. The narrative cleverly integrates world-building through Rimuru's "Great Sage" skill, presenting complex information about magic and monsters in digestible, list-based formats. Fuse juxtaposes mundane and fantastic elements by contrasting Rimuru's ordinary past life experiences—comparing skills to computer terms, using business negotiation tactics—with extraordinary events for comedic effect.

Rimuru Tempest distinguishes himself from typical isekai protagonists by focusing on infrastructure, government, and community welfare rather than pure combat dominance. In That Time I Got Reincarnated as a Slime, Vol. 1, he applies his contractor work experience to teach goblins about building, farming, and installing septic systems—prosaic tasks that ground the fantasy elements. Rimuru remains largely unaware of his true power level, which prevents him from becoming an insufferable perfect hero and keeps him relatable through his retention of human sensibilities and mundane thought processes.