If you loved Magic Tree House, try A Certain Magical Index: The Miracle of Endymion
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 both carry the cozy, playful mood tags, and they sit in Animation / Fantasy / Science Fiction 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 A Certain Magical Index: The Miracle of Endymion is
Technically, it's about a girl with a voice that could trigger an interdimensional quarrel, but mostly it's about hanging out at a space elevator. Touma, Index and a newcomer are enjoying the view when a magic-user shows up to spoil the vibe. All they wanted was a nice afternoon, not a plot device.

