From Cireus-Anime website:

Tina Tia Lilu is a helpful and sweet girl from Wind Up Village on Wind Up Island. When she and her friends find a boy inside a waterfall, Tina discovers that the "mysterious traveler" is not like her.

But strange things are happening around her. Dr. Weirdlaff and his cronies are up to something, and Tina tries to understand her strange feelings toward the boy who came down from the rainbow as an adventure she never expected unfolds.