An explosion has happened at the symbol of Osaka, Nichiuri TV! Then in the facility an interview held by Satsuki-kai, a leading organization in the competitive karuta world, is going to be recorded. The explosion causes great panic. The only people left inside the crumbling building are Heiji Hattori, the high school detective of the West, and his childhood friend, Kazuha Toyama. Fortunately, they have a narrow escape thanks to Conan, who rushes to the scene. The incident is just like a terrorist attack. However, the motive of the bomber is unknown. Before the explosion, Conan and others encounter a mysterious beautiful girl, Momiji Ooka. Much to their surprise, she refers to Heiji as her future husband. Moreover, Momiji Ooka turns out to be the High School champion of the karuta game. As fate would have it, Kazuha Toyama is going to challenge Momiji to a karuta competition over Heiji, so she begin to train intensively under the guidance of Heiji's mother, Shizuka, who is a skilled karuta player.Meanwhile, in a traditional Japanese house in Arashiyama, Kyoto, the champion of last year's Satsuki Cup has been found murdered. At the crime scene, Momiji is seen in a video. Besides, many karuta cards were scattered meaningfully around the victim. How is Momiji connected to the murder? Together with the Osaka and Kyoto police departments, Conan and Heiji launch an investigation into the two incidents.
