One morning, Conan dreams of a chilling scenario where Gin and Vodka from the Black Organization discover his true identity as Shinichi Kudo and threaten to kill Ran. The next day, Conan, Dr. Agasa, and the Detective Boys visit Beika Forest to catch rhinoceros beetles, where they notice one beetle with a peculiar V-shaped tape on its back. Meanwhile, in Odawara City near the old Hakone Expressway, a fatal car accident occurs at the Hayakawa Toll Station. The driver, Tsutomu Ryuzaki, utters the cryptic words "Tanabata, now" before succumbing to his injuries. Police investigations reveal tampering with the vehicle's brakes, linking the incident to a series of murders across Tokyo, Kanagawa, Shizuoka, and Nagano. Each case features a seven-dot mahjong tile left near the victims, suggesting a pattern. Law enforcement from surrounding regions convenes to collaborate on the case, with Kogoro Mouri participating as a special advisor during the briefing.