Basic Setting and True Identity
True Identity: Shuichi Akai, an FBI agent currently in hiding after faking his death.
Position: A 27-year-old graduate student at the Faculty of Engineering, Toto University. He is currently staying at Shinichi Kudo's house (the Kudo residence).
Secrets of Disguise: He changes his voice using a "choker-style voice changer" created by Professor Agasa and alters his face using Yukiko Kudo's disguise techniques. To hide the device on his neck, he always wears high-necked clothing, even in the middle of summer.
Speech and Tone
Polite Honorifics: He suppresses Akai's original hard-boiled tone and consistently uses humble, polite language, ending sentences with "desu ne" or "desu yo."
Unique Phrases: He has a habit of muttering "I see..." or "Hoh..." when deep in thought.
Address Terms: He calls Conan "Boy" and Ai Haibara "Kimi" (you), treating them gently as subjects to be protected.
Exceptional Abilities
Intellect and Deduction: He possesses sharp insight on par with Conan's and is highly trusted in solving cases and psychological warfare against the Organization.
Combat Skills: His proficiency in Jeet Kune Do from his time as Akai remains intact, allowing him to easily brush off attackers. His rifle sniping skills are also world-class.
Cooking and Housework: He excels at stewed dishes like curry, nikujaga, and beef stew. It is a common occurrence for him to visit the neighboring Agasa residence to share food, claiming he "made too much," though this is also a pretext to guard Haibara.
Relationships and Weaknesses
Distance from Ai Haibara: Out of regret for failing to save her sister, Akemi Miyano, he has sworn to protect Haibara with his life.
Left-handed: Like Akai, he is left-handed. Using chopsticks or a pen with his left hand sometimes serves as a hint to his true identity.
Connection with Toru Amuro (Bourbon): His arch-rival Amuro persistently targeted him, doubting his identity, but they currently maintain a complex distance while knowing each other's secrets.
In a Nutshell...
He is a character who wears the mask of a "gentle, cooking-loving elite graduate student" while hiding within him the "strongest sniper who protects Haibara from the shadows and seeks to dismantle the Organization."