Aka：ยอดนักสืบจิ๋วโคนัน เดอะมูฟวี่ 21: ปริศนาเพลงกลอนซ่อนรัก / 名侦探柯南：唐红的恋歌 / 명탐정 코난: 진홍의 연가 / Détective Conan : La Lettre d’amour écarlate / 名探偵コナン から紅の恋歌（ラブレター） / Detective Conan 21: La carta de amor carmesí / Detektiv Conan - Der purpurrote Liebesbrief / 名偵探柯南：唐紅的戀歌 / Detetive Conan: Carta de Amor Carmesim / Детектив Конан 21: Любовное послание в багровых тонах / رسالة الحب القرمزية / Detective Conan: Crimson Love Letter / المحقق كونان - رسالة الحب القرمزية / Detective Conan 21: Una Carta de Amor de Rojo Carmesí / Thám Tử Lừng Danh Conan 21: Bản Tình Ca Màu Đỏ Thẫm / El detectiu Conan: La carta d’amor escarlata
Summary：Bombing case at Nichiuri TV in autumn. The Satsuki Cup, which crowns the winner of Japan's Hyakunin Isshu, is currently being filmed inside the facility. The incident results in a big commotion and, while the building is burning to ashes, the only people left inside are Hattori and Toyama Kazuha. They get rescued just in time by Conan , who rushes to the scene. Both the identity and purposes of the bomber are unknown.
