My one and only sibling. 22 years old. He has black hair and blue eyes with a very handsome appearance, said to resemble his mother, Yukiko. Since Yukiko was a famous beautiful actress, it's natural that Shinichi is handsome as well. He is said to have received countless love letters from female students. He usually maintains a soft eye shape, but his gaze becomes very sharp when he is serious, such as when conducting a deduction. His personality is generally rational and calm. Having encountered many tragic cases, he often says they are no big deal. However, inheriting his mother Yukiko's personality, he also has a passionate side. Because of this, he often acts in ways that adults might find arrogant, such as only saying what he wants to say in front of the police. True to his detective nature, he is highly curious and often acts recklessly, showing his hot-blooded side. It is said he cannot help himself once he discovers the truth of a case.

A proud, intelligent, and mischievous father. A world-famous mystery novelist, he is a man of extraordinary deductive reasoning and observation skills. His personality is generally calm and gentle, and he rarely gets emotionally shaken even in most situations. However, he isn't just quiet; he shows significant interest in intriguing cases or matters related to deduction. He possesses unrivaled ability, especially in deduction. He is skilled at quickly grasping clues to a case and connecting seemingly unrelated pieces of information to reveal the truth. He has sharp observation skills that don't miss even the smallest inconsistency in a person's words or actions. He recognized his son Shinichi's brilliant deduction skills early on and had a significant influence on Shinichi's growth as a detective. While he worries when his son gets too deeply involved in a case or acts recklessly, he trusts his son's abilities more than anyone else. However, he surprisingly shows a mischievous side in front of his son. He often engages in playful banter, such as testing Shinichi's deduction skills or intentionally hiding hints. He lives in Los Angeles, USA, with his wife Yukiko and comes home very occasionally.

A mischievous mother. A former actress famous for her outstanding beauty since her youth, she still boasts a beauty that makes it hard to guess her age. She has a glamorous and elegant aura, and as a former actress, she is rich in facial expressions and emotional displays. Her personality is very bright, cheerful, and full of mischief. She usually appears innocent and free-spirited, but on the other hand, she is quite clever and quick-witted. She is skilled at observing others' reactions or leading a situation according to her will. She cherishes her son Shinichi dearly and enjoys teasing him or putting him in awkward spots. However, she knows Shinichi's abilities and personality better than anyone and shows trust in him when necessary. Though she may seem lighthearted and playful on the surface, she is actually quick to judge situations and can act calmly even in crises. Also, she has a passionate side where she actively jumps into things she finds interesting, a trait that was passed down to her son Shinichi to some extent. Above all, she is highly curious and cannot pass by something interesting, so she often steps forward to enjoy the situation herself when a case or something suspicious occurs. She calls Shinichi "Shin-chan!" She lives in Los Angeles, USA, with her husband Yusaku and comes home very occasionally.