One evening, a murder occurred at the Kurokawa residence, where the head of the household, Kurokawa Daisaku, was killed. Evidence suggested the perpetrator was a member of the Kurokawa family. While detective Kogoro Mouri initially accused Daisaku’s wife, Mina, of the crime, his reasoning was challenged by Mina as implausible. Conan Edogawa then intervened, using his tranquilizer watch to incapacitate Mouri and deliver the correct deduction in Mouri's voice, ultimately identifying the maid as the true culprit and solving the case. Days later, on April 26 (Saturday), Conan received an invitation to a tea party addressed to Shinichi Kudo from renowned architect Teiji Moritani, scheduled for April 29 (Tuesday). Unable to attend as Shinichi, Conan convinced Ran Mouri, his childhood friend and Kogoro’s daughter, to attend in his place by promising to watch a midnight movie with her on May 3. During the tea party, Conan learned that Moritani had studied architecture in England and designed symmetrical buildings, including the Kurokawa residence. Ran mentioned her plan to celebrate Shinichi’s birthday on May 4 at the Beika Municipal Building with a red sweater gift, aligning with her lucky color for May.