If you loved Detective Conan: Sunflowers of Inferno, try Case Closed: The Crimson Love Letter
A bridge between a film you've already seen and one most people haven't. Here's what they share, and what the second one does that the first one doesn't.
You already loved

Detective Conan: Sunflowers of Inferno
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Case Closed: The Crimson Love Letter
What they share
Both films are directed by Kobun Shizuno, and they sit in Animation / Crime / Mystery territory. If that's the register that drew you to Detective Conan: Sunflowers of Inferno, the second film will land in a comparable space — through a different lens.
What Case Closed: The Crimson Love Letter is
Osaka, fall. Charred playing cards. A bombing at a TV station interrupts a হাইকু competition; Conan arrives to rescue Heiji and Kazuha from the blaze. The bomber's motives remain unclear. Prime late-period Conan for those who like their mysteries extra-crispy.