Lyuze is a female robot and a former guardian of the mysterious girl Luna, who was revered as a savior. Before the cataclysm known as the Ruin, Lyuze served alongside her sister Liza, the warrior known as the God of Death Dune, and another guardian named Niko. Their sole purpose was to protect Luna. When the cyborg Casshern, acting under orders, killed Luna, the event triggered the Ruin, a devastating phenomenon that caused the world to decay and brought all robots closer to death. In the ensuing chaos, Lyuze's sister Liza was fatally injured by Casshern and eventually succumbed to corrosion. This loss consumed Lyuze with a singular, burning desire for revenge against Casshern, whom she blamed for both the death of her sister and the destruction of her world.

At the start of the story, Lyuze is driven entirely by vengeance. Her personality is cold, distant, and determined, marked by a deep, simmering anger. She tracks Casshern across the ruined world, waiting for the right opportunity to kill him. However, when she finally confronts him and he makes no effort to resist, allowing her the chance to strike him down, she hesitates. She cannot bring herself to kill him when he is defenseless and seemingly remorseful. Instead of exacting her revenge, she chooses to follow and accompany Casshern on his journey.

As Lyuze travels with him, she witnesses his struggle with his lost memories, his profound guilt, and his suffering. She sees him protect the weak and grieve for the fallen, gradually recognizing that he is no longer the ruthless assassin he once was but a deeply troubled soul seeking atonement. This forces her to confront her own beliefs, and her hatred slowly transforms into understanding and sympathy. She lets go of her anger, choosing to stand by Casshern not as an enemy but as a trusted companion. Over time, her feelings deepen into love, making her one of the few people who truly understand and support him. Lyuze's journey is one of profound emotional growth, as she transitions from a life defined by a destructive need for revenge to one embracing forgiveness, companionship, and love. In the final episodes, she finds true happiness and peace, dying contentedly in Casshern's arms, stating that she lived her life to the fullest.

In terms of abilities, Lyuze is a skilled and capable warrior, a product of her previous role as one of Luna's elite guardians. She is strong, agile, and proficient in combat, which allows her to survive the dangerous, decaying world and to effectively track and confront her quarry. Her true strength, however, lies in her emotional resilience, her capacity for deep feeling, and her ability to undergo a complete moral and emotional transformation. Her key relationships define her arc. Her bond with her sister Liza is the foundation of her initial vendetta, while her evolving relationship with Casshern, moving from hatred to intimate love, is the central pillar of her story. She also shares a common pain with Dune, another former guardian of Luna, as both struggle with their loss and purpose in a dying world.