Jozak Gurrier is a supporting character in the series, serving as a spy and personal bodyguard to the protagonist. He is a childhood friend of the Mazoku soldier Conrad Weller, with whom he shares a long and trusting history. His heritage marks him as half-Mazoku and half-human, a background that carries significant weight in the world he inhabits. He survived the Battle of Lutenburg, a conflict where those of mixed blood were forced to prove their loyalty.

In terms of appearance, Jozak is a well-built man with bright orange hair, which is parted down the middle with the back kept long, and blue eyes. His typical attire consists of a tattered brown vest worn over a black short-sleeved shirt.

His personality presents an intriguing duality. As a spy, he is shrewd, observant, and does not grant his trust easily, often requiring others to prove their character before he accepts them. He is also a skilled actor, able to adopt any necessary persona to complete his missions, and can be unsympathetic and merciless in battle when the situation demands it. Despite these serious traits, Jozak is generally light-hearted, overtly friendly, and fiercely loyal to those he serves, particularly the demon king. He possesses a capacity for compassion and can withhold judgment about people even while harboring suspicions about their nature.

One of Jozak’s most distinctive and recurring traits is his habit of cross-dressing, particularly when undertaking stealth missions. He is frequently seen disguised as a woman, such as a nurse or a maid, and has even won a drag-queen competition. This is not merely for comic relief; the practice originated because cross-dressing once saved his life, and he continues it as a personal good luck charm.

Regarding his motivations and role in the story, Jozak is initially wary of the newly summoned demon king, Yuuri, fearing that Yuuri might repeat the destructive mistakes of a previous ruler named Stoffel. However, he is loyal to the position of the demon king and eventually forms a close personal relationship with Yuuri. He aids Yuuri in claiming the demon sword Morgif, inspiring the young king not to be afraid of the weapon. To test Yuuri's worthiness as a leader, Jozak once deliberately enrolled him in a dangerous gladiatorial competition, demonstrating his commitment to ensuring the new king is strong and capable. Despite such tests, he is a devoted protector, and Yuuri entrusts him with guarding Morgif's power source, the jewel, during a critical moment. Yuuri gives him several affectionate nicknames, including Ms. Biceps, Oniwaban, and The Spy.

Jozak possesses no magical abilities, but his physical and combat skills are formidable. He is a highly qualified soldier and a master of disguise, relying on his speed, strength, and exceptional swordsmanship to carry out his duties. He is also proficient in hand-to-hand combat and demonstrates surprising practical skills, including carpentry and woodworking.