Magic Tree House: The Three Secret Keepers

Sasha, Vicky, and Ieva, three girls who lives peacefully with their families in the countryside of Florida, had found a mysterious tree house that had appeared in the nearby forest when they were all out riding in their Grandfather's apple orchard.
After a few weeks working with Merlin, they all accepted to become Meilin's apprentices.The three of them was sent to Japan to send a message to the ninjas, but it turned out harder than they think.