If you loved Magic Tree House, try Trinity Seven: Eternity Library & Alchemic Girl
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.
What they share
Both films are directed by Hiroshi Nishikiori, and they sit in Animation / Fantasy territory. If that's the register that drew you to Magic Tree House, the second film will land in a comparable space — through a different lens.
What Trinity Seven: Eternity Library & Alchemic Girl is
Here's one for the "anime fans only" shelf. Our hero accidentally conjures a precocious child, Lilim, from a magic book, which also awakens the dreaded White Demon Lord. Cue the final battle, so our heroes can save the world, again.

