TV-Series
Description
Kenichi Yoshii is a supporting character in the series, known for his role as a young and highly skilled engineer. He operates under the code name 09, also read as Zero Nine, and is a former member of the CCC, a controversial organization.

Kenichi is a teenager who is initially below average in build and height for his age, standing at 161 cm. He has short, ear-length beige hair styled in a manner resembling a bowl cut and light green eyes, which he conceals behind a pair of rectangular glasses. As the story progresses, his appearance matures; he grows his hair out to about shoulder length and develops a taller, slightly more muscular build. He was born on April 2nd.

In terms of personality, Kenichi is highly intelligent and withdrawn, preferring to work in the background rather than on the front lines. He is described as meek and kind-hearted, with a strong capacity for sympathy. Unlike some members of the CCC who are driven by hatred for devils, Kenichi's motivation for joining the organization stemmed from a deep admiration for its leader, Kirio Kikuhara, and a desire to be by his side. Initially, he lacks self-confidence, but over the course of the narrative, he develops a stronger sense of self and the courage to stand up for himself and those he cares about, becoming more honest and straightforward.

His background reveals a lonely childhood. After the death of his parents, Kenichi was taken in by his aunt, uncle, and cousin, from whom he felt emotionally distant. He spent much of his time alone, studying and working on a computer left to him by his father. This led him to discover a natural talent for hacking. His skills eventually drew the attention of the authorities when he broke into a police network. Instead of being arrested, he was recruited by Kirio Kikuhara, who wanted to utilize his abilities. At the age of 15, Kenichi left his relatives' home to become the CCC's hacker and engineer.

Within the story, Kenichi serves as the technical backbone for the CCC's field operations. He is responsible for developing much of the technology the organization uses, including the thermography scope and a GPS tracking system to monitor its members. Despite his talents, he is not a frontline fighter. His role often involves hacking, surveillance, and providing technical support from a secure location.

Kenichi's most significant relationship is with his partner, Nanako Tenjo, also known as Zero Seven. He harbors a genuine crush on her, though he initially lacks the courage to approach her directly. This insecurity manifests in a rather unhealthy habit of secretly taking photographs of her while she sleeps. As the plot develops, Kenichi learns of an internal plan within the CCC to have Nanako eliminated. This revelation serves as a major catalyst for his character development. Choosing to protect her above all else, he abandons his previous behavior and decides to become her true friend. He defects from the CCC alongside her, demonstrating his newfound resolve and loyalty.

Kenichi does not possess any supernatural abilities, as he is fully human. His notable abilities lie entirely in his intellect and technical prowess. He is an exceptional hacker capable of breaching secure networks and an ingenious developer who creates advanced technological devices for field use.