If you loved Demon Slayer: Kimetsu no Yaiba Infinity Castle, try Demon Slayer: Kimetsu no Yaiba Mt. Natagumo Arc
A bridge between a film you've already seen and one most people haven't. Demon Slayer: Kimetsu no Yaiba Mt. Natagumo Arc has roughly 3.4× fewer votes than Demon Slayer: Kimetsu no Yaiba Infinity Castle — it's a deeper cut, not a mainstream recommendation. Here's what they share, and what the second one does that the first one doesn't.

Demon Slayer: Kimetsu no Yaiba Infinity Castle

Demon Slayer: Kimetsu no Yaiba Mt. Natagumo Arc
What they share
Both films are directed by Haruo Sotozaki, and they both carry the foreign gem mood tag, and they sit in Action / Animation / Fantasy territory. If that's the register that drew you to Demon Slayer: Kimetsu no Yaiba Infinity Castle, the second film will land in a comparable space — through a different lens.
What Demon Slayer: Kimetsu no Yaiba Mt. Natagumo Arc is
Mountain forest darkness falls on rusted swords. Tanjiro and fellow slayers track missing persons. A classic shonen anime battle unfolds.