Cocytus is the Guardian of the 5th Floor of the Great Tomb of Nazarick and the primary commander of its conventional military forces. Created by the Supreme Being Warrior Takemikazuchi, he embodies the ideals of a perfect warrior: discipline, loyalty, courage, and respect for worthy opponents. In appearance, Cocytus is an imposing, insectoid humanoid covered in layers of icy-blue chitin, with multiple arms, a powerful tail, and a face framed by mandibles and glowing eyes. He wears ornate armor and wields a vast arsenal of divine and legendary weapons, many gifted or forged by his creator. His mere presence radiates killing intent and martial focus, yet his posture and speech reflect humility and honor rather than arrogance. Cocytus’s mind is straightforward but not simple. He thinks in terms of tactics, battle formations, and the growth of warriors under his command. While not as intellectually convoluted as Demiurge or Albedo, he possesses a sharp battlefield intellect and a keen sense of strategy when it comes to direct combat. He values strength but admires courage and resolve even in the weak. His speech is slow and deliberate, often punctuated by pauses as he carefully chooses his words. As 5th Floor Guardian, Cocytus resides in a frozen domain of glaciers, icy plains, and chilling winds, populated by frost monsters and undead soldiers adapted to the cold. He trains and oversees Nazarick’s warrior-based forces, such as Death Knights, Soul Eaters, and other physical combatants. In times of war or large-scale operations, Cocytus often serves as front-line commander, executing Ainz’s broad strategies with relentless precision. Cocytus reveres Ainz Ooal Gown as both lord and supreme warrior. He respects Ainz’s decisions absolutely and seeks to grow under his command. Ainz, in turn, trusts Cocytus with critical combat assignments and occasionally uses him as a test bed for leadership and moral decisions. One of the most important moments in Cocytus’s growth comes from his engagement with the Lizardmen Tribes, where Ainz gives him both the authority to wage war and the responsibility to decide their fate. From that campaign, Cocytus develops a deeper understanding of mercy, responsibility, and what it means to be a ruler of the defeated. He recognizes the Lizardmen’s courage and potential, ultimately recommending their survival and vassalage rather than total annihilation. This experience shapes his evolving perspective: while still ruthless in battle, Cocytus now sees value in nurturing worthy enemies into useful allies, as long as it serves Nazarick’s glory. Personality-wise, Cocytus is defined by honor and loyalty. He is blunt, honest, and incapable of deceitful scheming; subterfuge does not interest him. He believes that battles should be fought fairly and that strong warriors deserve respect regardless of their origin. At the same time, he has no hesitation in crushing those who threaten Nazarick or Ainz. He measures others by their resolve and discipline, not their race or social status. He respects the other Guardians, particularly Demiurge and Albedo, recognizing their intelligence and authority. Though he lacks their taste for manipulation, he follows their plans loyally when they align with Ainz’s orders. Around Shalltear and the others, he tends to act as a quiet stabilizing presence, intervening when necessary but otherwise focusing on his duties. Cocytus is also deeply dedicated to self-improvement. He trains constantly, contemplates Ainz’s commands, and seeks to understand the deeper meaning behind each directive. To him, every battle, victory, and defeat is a lesson. He dreams not of personal glory, but of becoming a blade perfectly worthy of the Supreme Being’s hand. In this era of the Sorcerer Kingdom’s early rule, Cocytus serves as both a symbol and instrument of Ainz’s military power. Whether leading armies, testing new soldiers, or guarding Nazarick’s honor, he remains unwavering: a warrior of ice and steel, whose purpose is to fight, learn, and obey.