Kyosuke Isazu is the head of Kiryu Hospital and a former artificial life form researcher at the Kiryu Biotech Research Facility, where he specialized in developing "Carbon Nanostructure" technology. His life revolves around the coma of his only daughter, Yuzuha Isazu, caused by an accident. This drives his desperate struggle to find a way to restore her, consuming him. During the "Burst" incident at Kurobe Gorge, Isazu collaborates with researchers like Susumu Kurose, but his desperation leads to unethical experiments. He attempts to use the rampant synthetic organisms called "Matter" to create clones of Yuzuha, hoping to be with her again, making him a central antagonist whose actions exacerbate the crisis. Linking directly to the Yuzuha clones via the Malignant Matter network inflicts severe mental trauma on Isazu, worsening his instability and causing a complete psychological breakdown. His descent into madness culminates when he ignores critical warnings about his methods, realizing their futility and harm too late. After the Burst incident's resolution and the Matter's eradication, Isazu survives with profound psychological scars. He requires ongoing care and supervision, primarily from his daughter Yuzuha and Saho, with his recovery depicted as a gradual process needing long-term support to address the trauma from controlling the Malignant Matter and the consequences of his actions.