Minoru Kokubunji (国分寺 稔 Kokubunji Minoru?) is a wealthy twelve-year old genius, whose specialty is persocoms. In particular, he has built a custom persocom named Yuzuki, designed to look like his late sister, and has given her self-teaching software, meaning that she can learn things on her own instead of having to have programs loaded into her as is the case with most persocoms.
For the most part, Minoru is a very reserved and soft spoken individual who surrounds himself with persocoms. His curiosity over Chi's origins leads to him becoming one of Hideki Motosuwa's closest friends. Minoru does what he can to help his friends whether it be technological help, such as tracking things down or allowing Hideki to make video phone calls, or advice on relationships with persocoms. Although he is known for being calm and collected most of the time, Minoru's attitude completely changes when Yuzuki is present. Similar to Hideki's behavior toward Chi, Minoru is very protective of Yuzuki and is prone to outbursts whenever she is in trouble. He is also very forgiving, always comforting her on the fact that it is never her fault if something goes wrong.