Minoru Kokubunji is a supporting character in the anime Chobits. A twelve-year-old prodigy, he attends the prestigious Kiyozono Academy and lives alone in a large mansion. Despite his youth, his knowledge of Persocoms is unrivaled, possibly surpassed only by Chitose Hibiya. His expertise comes partly from personal loss: his parents are presumed deceased, and approximately two years before the story begins, his elder sister, Kaede Saito, died of an unknown illness. Deeply affected by this, Minoru constructed a custom Persocom named Yuzuki, basing her personal data and appearance entirely on his late sister as a way to cope with the absence. In addition to Yuzuki, he has also built four custom female maid Persocoms.

Minoru is generally courteous, well-mannered, and reserved. He is soft-spoken and surrounds himself with his work, but he is always ready to assist his friends when they need help. He is calm and collected most of the time, but his demeanor changes noticeably when Yuzuki is involved; he is prone to emotional outbursts if she is in trouble, similar to how the protagonist Hideki reacts when his Persocom Chi is in danger. He also possesses a mild, mischievous, and slightly perverted side, as evidenced by his habit of dressing his maid Persocoms in revealing outfits, often to get a reaction from guests. Despite this playful streak, he is a very forgiving character, frequently reassuring Yuzuki that she is not at fault when something goes wrong.

Minoru's primary motivation stems from his unresolved grief over his sister's death. By creating Yuzuki, he attempts to preserve Kaede's memory and keep a version of her with him. This personal project also drives his broader interest in the capabilities and limits of Persocom technology. He becomes one of Hideki Motosuwa's closest friends after Hideki discovers Chi, a mysterious and seemingly unique Persocom. Minoru had initially met Hideki's friend Hiromu Shinbo through an online Persocom bulletin board system, where Minoru uses the username M, and through Shinbo, he meets Hideki. Recognizing that Chi may be one of the legendary Chobits, a rumored series of Persocoms with free will and emotions, Minoru takes a keen interest in her origins and helps Hideki investigate. He understands the nature of Hideki's relationship with Chi and offers support whenever possible, often meeting with him at Minoru's preferred hangout, the Duklyon Cafe. His technical abilities are crucial to the story, most notably when he uses a GPS map anonymously provided by the character Zima and cross-references it with his own Persocoms to locate Chi after she is kidnapped.

Throughout the series, Minoru remains a steady and reliable presence, using his deep technical knowledge to aid the main characters in their quest to understand Chi. His own personal development mostly revolves around his attachment to Yuzuki. While his grief-driven creation of Yuzuki suggests a refusal to fully let go of the past, his interactions with her and with Hideki gradually show his capacity to care for her as her own person, even while she serves as a substitute for his lost sister. His key relationships are with Hideki, whom he supports as a fellow Persocom owner facing unique emotional challenges; with Shinbo, whom he befriends online and in person; and most importantly with Yuzuki, his custom creation who represents both his greatest technical achievement and his emotional vulnerability. His notable abilities include advanced Persocom construction and programming, deep knowledge of Persocom hardware and software that allows him to diagnose and understand even highly unconventional units like Chi, and effective use of his network of custom Persocoms for tasks such as tracking and data analysis.