Kazuma Narusawa is one of the main characters from the anime and manga series Tantei Gakuen Q, serving as a member of the prestigious Class Q at the Dan Detective School. He comes from a wealthy family as the son of the president of the Narusawa Industries conglomerate. Kazuma is a recognized prodigy in the field of computer technology, having established himself as a successful and well-known computer game programmer from a very young age, reportedly creating his first game at the age of seven.

His primary defining characteristic is his genius-level intellect, particularly in areas related to programming, decryption, and mathematical puzzles. He is almost always seen carrying a laptop computer, which he uses as his primary tool for gathering and analyzing information. Kazuma has even developed his own detective software, including search engines, case files, and a program he calls "deduction software" that organizes data based on past case records to help solve new mysteries.

In terms of personality, Kazuma initially presents as proud, self-confident, and somewhat arrogant. He has a strong belief in the power of technology and data, often preferring to rely on his machines and analytical tools rather than intuition or physical investigation. At the beginning of his time at the Dan Detective School, he was dissatisfied with being placed in Class Q, which he mistakenly believed to be the lowest-ranked class. His desire for status led him to seek a transfer to the top-tier Class A. However, a significant turning point in his character occurs when his new classmates come to his aid during a difficult investigation involving a coded dying message on a computer. This event makes him realize that his peers genuinely care for him, leading him to abandon his transfer request and fully embrace his place in Class Q.

Kazuma's role in the story is that of the team's technical specialist. While other members of Class Q often take the lead in on-site physical investigation or intuitive leaps of logic, Kazuma typically remains in a support role, gathering information remotely, cracking codes, and providing technical insights. He is particularly valuable for solving math-based tricks and complex ciphers, with his abilities in decryption being acknowledged as superior even to those of professional detectives. Despite his brilliance, he is sometimes criticized by his friends for treating real-life criminal cases too much like games and for an over-reliance on his machines rather than human perception and emotion.

His key relationship within the group is with Kintaro Toyama, or Kinta. The two share a friendly but constant rivalry, which stems from their completely opposite approaches to detective work. Where Kazuma is calm, logical, and relies on technology, Kinta is passionate, physical, and relies on instinct and strength. This contrast makes them frequent foils for one another, and they are often the target of each other's jokes and competitive banter. While they bicker, this rivalry is based on mutual respect and is a core dynamic of the group.

Throughout the series, Kazuma shows notable development. He overcomes his initial classism and arrogance, learning the value of friendship and teamwork. He also confronts a unique psychological quirk: early in the anime, it is implied that he struggles to solve cases correctly without wearing his lucky hat. By the end of the television series, he appears to have outgrown this dependence, gaining faith in his own abilities rather than relying on a charm. His skills as a programmer allow him to create invaluable tools for the team, helping them tackle challenges that brute force or traditional detective work cannot solve. While some of his observational talents, such as a keen eye for detail that extends to accurately noticing personal details like clothing sizes, are established, he is most consistently defined by his technical genius and his growth from a solitary prodigy into a collaborative team member.