Mitsuhiko Tsuburaya, a first-grade student at Teitan Elementary School, co-founds the Detective Boys with Genta Kojima, Ayumi Yoshida, and Conan Edogawa. This follows their investigation of a seemingly haunted mansion, which uncovers an old homicide case. Though initially skeptical about ghosts, he joins subsequent adventures like an Italian gold coin treasure hunt that solidifies the group. Both his parents are school teachers, and he has an older sister named Asami Tsuburaya, roughly ten years his senior. Raised to prioritize politeness, he consistently uses the formal "-san" suffix for elders regardless of familiarity. Scientifically minded and analytical, Mitsuhiko often references science books and employs empirical methods. He proactively prepares for scenarios, meticulously logging clues in his Detective Boys notebook—a habit that later deciphers critical coded riddles in a murder case. He finds deep satisfaction in studying science, history, and trivia, sometimes impressing peers like Ayumi. Despite intellectual pursuits, he enjoys childhood pastimes like treasure hunts and snowman-building. He avoids eating carrots, always leaving them uneaten until last. Resourceful and increasingly confident, Mitsuhiko displays leadership across cases. In "The Desperate Revival," he solves a cavern escape riddle after Conan collapses. During "Mushrooms, Bears, and the Detective Boys," he administers first-aid to an injured Haibara—learned from Conan—and devises a coded signal for rescue, sparking his romantic feelings for her. His dedication surfaces in "Mitsuhiko's Mystifying Forest," where he risks entering a forest to catch fireflies for Haibara and Ayumi, encountering an escaped serial killer who spares him over shared appreciation for the insects. In "Mountain Witch's Cutlery," his observation of a suspect sharpening a cleaver with a threatening expression provides key evidence. Non-canon stories like "Countdown to Heaven" reveal Mitsuhiko confiding in Ran about equally liking Haibara and Ayumi, questioning if this makes him "a bad person." He later rescues Haibara in danger, vowing to "never let go." His relationships include a friendly rivalry with Genta, admiration for Conan’s deductions, and occasional jealousy over Ayumi’s attention to Conan. He interacts respectfully with adults like Professor Agasa and Detective Takagi. Slim-framed with short brown hair, messy bangs, and freckles, Mitsuhiko typically wears short-sleeved shirts and long pants. As the Detective Boys’ information specialist, he explains complex concepts to Genta and Ayumi and spots overlooked details during investigations. His development showcases growing deductive skills while retaining age-appropriate vulnerabilities.