Wataru Takagi is a police sergeant and detective within the Tokyo Metropolitan Police Department's Criminal Investigation First Division. He transferred to the division roughly three years prior, following a significant bomber case. Early in his career, he was mentored by Detective Wataru Date, whose death one year before the current timeline deeply affected him. Takagi first met Conan Edogawa during the investigation of actress Isami Nagakura's murder, assisting Inspector Megure and helping expose the case's trick involving identical rooms. Takagi harbors longstanding romantic feelings for fellow detective Miwako Sato. Their relationship develops through several critical incidents, overcoming interference from colleagues like Inspector Shiratori. A key moment occurs when Sato kisses him after he is hospitalized during a dangerous case; they share additional kisses in Episode 683 after he narrowly survives a bomb accident. Their bond faces a test during a fake wedding drill at Shibuya Hikarie in "The Bride of Halloween" when Takagi leaps to protect Sato from a simulated armed intruder. This action evokes her traumatic memories of Jinpei Matsuda's death—a bomb squad detective she loved who died in a serial bombing three years earlier. Personality-wise, Takagi initially presents as self-conscious and nervous, yet demonstrates strong dedication and competence in his work. He possesses sharp intuition, a firm sense of justice, and a self-sacrificing nature, consistently prioritizing others' safety. He holds deep respect for Sato both professionally and personally, often deferring to her judgment. His hobbies include playing the maracas and following international wrestling, allowing him to recognize moves like Keiji Mutoh's "Shining Wizard". During investigations, Takagi stands out as one of the few officers who consistently trusts Conan Edogawa's insights, sometimes allowing him to take the lead—such as when Sato is handcuffed to a suspect. In "The Bride of Halloween", he disguises himself as the deceased Matsuda to negotiate with kidnappers after Detective Chiba is abducted. This leads to a confrontation with Elenica Lavrentyeva, leader of the vigilante group Nado Unichtozit, where Takagi's bravery proves pivotal. He interacts warmly with the Detective Boys, accompanying them during Halloween activities; they affectionately call him "Takagi-niisan" (Brother Takagi). He maintains polite and formal relationships with colleagues like Yumi Miyamoto and superiors including Inspector Megure.