One day, Conan was resting at home because of a cold, and during this time he received a call from Huihara Ai. It turned out that Huihara had made the latest antidote for APTX-4869. Although it was only a trial product, Conan, who was determined to restore Kudo Shinichi's identity, still couldn't wait to rush to Dr. Agasa's laboratory. After taking the medicine, Shinichi finally returned to his original state, but everything around him seemed to have changed: the trees in the doctor's yard grew taller, many new buildings appeared, the physical education teacher became old, the classmates in the class were all unfamiliar faces, and even Genta, Mitsuhiko and Ayumi all became high school students. He found Huihara, who had also become a high school student, and learned that he had been taking antidotes for the past 10 years, which led to drug resistance, and he had been unable to return to his original state in the past 5 years. Conan, who was lost, watched the changes around him helplessly, and what hit him even more was that Xiaolan decided to give up Shinichi, who had no news, and marry Teacher Akasaka. Their love was also a dream, how could it end...