Ifrit is a high-ranking fire spirit, often referred to as the Flame Giant, who appears as a powerful and intimidating entity composed entirely of fire. His origins trace back to the Dwelling of Spirits, from which he was forcibly taken by the Demon Lord Leon Cromwell. Leon then sealed Ifrit within the body of a young girl from another world named Shizue Izawa. The intention was for Ifrit to completely possess Shizue, but her own willpower and Unique Skill prevented him from achieving total control. Instead, the two were forced into an uneasy coexistence, with Ifrit acting as a weapon for Leon, using Shizue's body to fight. This situation continued until a masked hero appeared and used an Anti-Magic Mask to suppress Ifrit's power, sealing him within Shizue.

Initially, Ifrit possessed very little sense of self, acting almost solely on aggressive impulses and instincts. He was a destructive force, responding to hostility with overwhelming firepower and lacking a developed personality or moral compass. However, after a long period of being sealed, his eventual defeat by Rimuru Tempest, and subsequent absorption into Rimuru's stomach, his character undergoes a dramatic transformation. Inside Rimuru, he is brought into a separate space with the Storm Dragon Veldora Tempest. The extended period of isolation and observation, combined with Veldora's influence, allows Ifrit to cultivate a genuine sense of self-awareness and individuality. Upon developing this new personality, Ifrit is characterized as being polite, serious, and respectful. He consistently speaks in a formal manner, even with those he is close to. He becomes a hard worker, a strategic thinker who develops hobbies like playing chess and reading tactical books, and shows a strict, almost stubborn adherence to logic. Over time, he even adopts a more sarcastic and witty tone with Veldora, which the dragon interprets as a sign of his growth.

Driven by his newfound self-awareness, Ifrit's primary motivation shifts from simple destruction to a profound sense of regret and a desire for redemption. He spends a great deal of time reflecting on his past actions, particularly the years he spent possessing Shizue Izawa. He deeply regrets the immense pain he caused her, especially the death of her friend Pirino, which he committed while he still lacked a proper sense of self. He understands that his deep admiration for Leon Cromwell created an irreconcilable conflict with Shizue, who hated the demon lord, and this lack of understanding prevented them from ever becoming allies. His primary goal becomes coming to terms with these past sins and learning from his observations of Rimuru and Veldora to become a better being.

In the story, Ifrit serves as a significant early antagonist. His violent rampage after breaking free from the aging Shizue serves as a major challenge for Rimuru early in his journey. After being defeated and absorbed, Ifrit's role transitions from a physical threat to a narrative device for character development. His presence inside Rimuru's stomach alongside Veldora creates the framework for the "Veldora's Journal" episodes, which recap events from the perspective of the two trapped beings. Their burgeoning friendship provides a source of quiet character moments and comic relief. Furthermore, Ifrit's skills and abilities are analyzed by Rimuru, who then adapts and uses them in future battles, integrating the fire spirit's power into his own arsenal.

Ifrit's key relationships are central to his character arc. With Shizue Izawa, his relationship was defined by conflict, incompatibility, and shared suffering. Ifrit admired Leon, while Shizue despised him. He was the source of her power and her curse, and he acknowledges that his failure to understand her sorrow is his greatest regret. Leon Cromwell is Ifrit's original master, whom he served loyally and deeply respected, a fact that he now reflects on with a sense of complicated loyalty. The most positive and transformative relationship is with Veldora Tempest. Inside Rimuru's stomach, Veldora becomes Ifrit's companion and mentor. The Storm Dragon helps him develop his new personality, and the two become friends, with Veldora regarding Ifrit as his second friend after Rimuru. Finally, his relationship with Rimuru Tempest is that of a defeated enemy who is given a second chance. Rimuru's absorption and subsequent actions inadvertently create the conditions for Ifrit's redemption and rebirth.

As an upper-class fire spirit, Ifrit possesses several notable abilities, all centered on fire and heat. His most powerful offensive skill is Flare Circle (also known as Flame Prison), a devastating area-of-effect attack where he turns his own body into super-heated gas to incinerate everything within a hundred-meter diameter. He is capable of creating weaker clones of himself, though they are vastly inferior to the original. He can also summon swarms of Salamanders, lesser fire spirits, to fight on his behalf. His fiery body is constantly surrounded by a maelstrom of incredibly intense flames that can vaporize incoming attacks like water-based projectiles. After his absorption, these skills are analyzed and replicated by Rimuru's Unique Skill, Great Sage, allowing Rimuru and his other subordinates, such as Benimaru, to utilize powerful flame-based techniques.

Ifrit's development across the series is perhaps his most defining feature. He evolves from a mindless, rampaging elemental into a thoughtful, introspective individual capable of regret and friendship. After being absorbed, he is not destroyed. Instead, through his forced cohabitation with Veldora, his self-consciousness grows remarkably. He learns from watching the outside world with Veldora, developing a personality, a sense of humor, and a deep-seated remorse for his past. This growth culminates in his eventual materialization as a follower of Veldora, allowing him to leave Rimuru's stomach and live a new life as an independent being, forever changed by his experiences.