If you loved Case Closed: The Crimson Love Letter, try Detective Conan: Sunflowers of Inferno
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

Case Closed: The Crimson Love Letter
→
Try this next

Detective Conan: Sunflowers of Inferno
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 Case Closed: The Crimson Love Letter, the second film will land in a comparable space — through a different lens.
What Detective Conan: Sunflowers of Inferno is
Auction hall summer evening spotlights on Van Gogh's Sunflowers. Kaito Kid vanishes with a replica. This anime bears a classic detective fiction stamp.