In of Detective Conan (titled "Once-A-Month Present Threat Case"), the "useful piece" likely refers to a specific clue or plot element that Conan uses to solve the mystery or progress the overarching narrative . 🧩 The "Key Piece" of the Case
Depending on what you are looking for, "useful piece" might also refer to: Detective Conan Episode 7
💡 : Fans often discuss this episode because of Conan's noticeably "chubbier" animation style, which was unique to the early production designs. In of Detective Conan (titled "Once-A-Month Present Threat
: Conan drops his guard and acts exactly like Shinichi, even mimicking Sherlock Holmes' deduction style. This leads Ran to notice the uncanny similarities between the "child" and her missing friend. ⚠️ Potential Mix-ups Detective Conan Episode 7