If you loved Black Butler: Book of Murder, try Detective Conan: The Million-Dollar Pentagram
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

Black Butler: Book of Murder
→
Try this next

Detective Conan: The Million-Dollar Pentagram
What they share
Theyboth carry the playful mood tag, and they sit in Action / Animation / Mystery territory. If that's the register that drew you to Black Butler: Book of Murder, the second film will land in a comparable space — through a different lens.
playful
What Detective Conan: The Million-Dollar Pentagram is
Late March. Hakodate’s warehouse district, a single dripping spout. A lawyer slumps in shadow, one arm still clutching a katana. Nearby, cherry blossoms swirl like pale signals. Nods to Lupin III by way of Gosho Aoyama’s arch plotting.