Kogoro and Conan are brought to an apartment to examine the death of a man named Yamamoto. It is presumed a suicide as evidence project he put a gun in his mouth and firing. His friend is suspected of murdering him as he left the crime scene without calling the police. When Kogoro is fed strawberries, Conan realizes who the murderer is.
After investigating Yamamoto's dentist, Conan tranquilizes Kogoro and reveals the murderer to be Yamamoto's neighbor, Yumi Suzuki. Conan reveals that Yumi Yamamoto's dentist assistant and deduces Yumi entered Yamamoto's apartment and offered to treat him. When he opened his mouth, Yumi shot him with a gun. She killed Nobuo Yamamoto due to the accident that happened 10 years ago. Her husband was still hospitalized and not waking up after Yamamoto hit him while driving with the influence of alcohol and also because he got distracted with his fascination of the butterflies. As evidence, Conan reveals that Yamamoto's coffee stirrer is actually Yumi's dental mirror.
