Mikuru Katsuhara, who goes by the nickname Micchon, is a computer programmer and a key member of the group that runs the Eden of the East service. She is the cousin of Kazuomi Hirasawa, the group's leader. Her physical appearance is typically that of a small, unassuming young woman with brown hair, hazel eyes, and a wardrobe that often includes a white shirt with blue sleeves featuring the word earth, dark blue shorts, pink tights, and white boots. Akira Takizawa occasionally refers to her as Mi-tan.

In terms of personality, Mikuru is very shy and reserved. She only becomes open and frank around people she is close to and trusts. At first glance, her expression often appears bored or emotionless, but she can be easily flustered. Despite her quiet demeanor, she is a brilliant programmer who possesses exceptional skill with computers. She is the programmer who created the image recognition software that forms the technological foundation of the Eden of the East service, making her contributions vital to the group's operations and the overall story.

Her primary motivation is to support the Eden group and its goals. She uses her technical expertise to help solve problems, hack systems when necessary, and maintain the group's software. While she is not the most outspoken member, her reliability and dedication make her a trusted asset. Within the group, she shares a close working relationship with Saki Morimi and has mutual respect for Yutaka Itazu, often called Panties, appreciating each other's abilities. Kazuomi, her cousin, relies on her technical skills to lead the group effectively. Throughout the series and the subsequent films, Mikuru remains a steady presence, applying her programming genius to assist in the unfolding mystery without undergoing a dramatic personal transformation. Her key ability lies in her intuitive grasp of computer systems, enabling her to develop sophisticated software and perform complex hacking that proves crucial to the group's survival and success.