Kazuma Satō, a Japanese teenager who died and was transported to a fantasy world, originates from the KonoSuba series. There, he leads a party tasked with defeating the Demon King, frequently finding his companions problematic. His transition to the Isekai Quartet world occurs when Megumin presses a mysterious button discovered by his party, transporting them to a school environment. In this new world, Kazuma becomes a student in Class 2 and serves on the Disciplinary Committee alongside Tanya von Degurechaff and Demiurge. He finds Tanya intimidating due to her militaristic background and fears Demiurge, perceiving him as a literal devil. Nevertheless, Tanya acknowledges his tactical usefulness, stating she would recruit him into the military if in her world. Kazuma finds this world less stressful than his original one and expresses no desire to return, making him unique in this preference. He exhibits a lazy and opportunistic personality, preferring relaxation but showing initiative in social interactions. His trickster nature manifests in misleading the 203rd Aerial Mage Battalion about giant toads and deceiving Captain Weiss about Valentine's Day. He is known for perverted behavior: stealing female underwear with his "Steal" skill, peeping on classmates during beach trips, and attempting to sneak into the nurse's office, actions that led to restraint by Tanya and Demiurge. Vanir's exposure of his intentions created negative impressions, like with Naofumi Iwatani. His relationships are multifaceted. He shares a mutual recognition with Subaru Natsuki as fellow former shut-in NEETs transported to fantasy worlds, though he declares Subaru a rival for perceiving his life as easier. They cooperate during events like the Sports Festival. Kazuma initially wanted to harm Julius upon meeting him, but their teams later formed an alliance during the cavalry game to counter teachers like Roswaal and Vanir. He defends Ainz Ooal Gown from Aqua's purification and, collaborating with Ainz, assists Raphtalia in locating Naofumi, calming her upon their encounter. Kazuma maintains complex ties with his original party members (Aqua, Megumin, Darkness). He often feels embarrassed by their behavior and tries to prevent public humiliation. Despite frequent criticism, he expressed genuine happiness when they gave him valentine chocolates. His history with Chris involves her teaching him the "Steal" skill, which he used to steal her underwear, and he occasionally teases her about this. Vanir, a former adversary, exposed Kazuma's inappropriate intentions during a physical examination. As an adventurer, Kazuma was considered the weakest in his original world but compensated with high intelligence, cunning tactics, and exceptional luck. His abilities adapt to the Isekai Quartet world: "Steal" becomes less effective against beings like Reinhard van Astrea due to divine protections; "Stealth" renders him undetectable to average individuals; "Snipe", reliant on luck, grants high projectile accuracy, used with a slingshot. His luck enables critical successes, like aiding Tanya in disabling the Mobile Fortress Destroyer during the cavalry event. A notable vulnerability exists: Chris reveals she cannot revive Kazuma if he dies in this world, unlike in his original one.