The day before her birthday, Akane is asked to retrieve her birthday present from her aunt Chi's shop. While looking around, she chances upon a mysterious slab with a hand-shaped cavity in it. Curious, she places her hand in it, and—to her surprise—it fits perfectly. The next thing she knows, a strange alchemist named Hippocrates and his apprentice Pipo appear, calling Akane the legendary "Goddess of the Green Wind."

The two eccentrics claim to be from a different world connected to the shop's basement. With the peace of their world in jeopardy, Hippocrates and Pipo seek the help of the only one capable of saving it from destruction: Akane. Forced to accompany them on a journey to restore the land's harmony, Akane—with her aunt in tow—sets off to discover a magical new place.

The Wonderland, known as Birthday Wonderland in Japan, the UK, and Ireland, is a 2019 film based on the 1988 children's novel Chikashitsu kara no Fushigi na Tabi (Strange Journey from the Basement). It was the last Japanese film to be released in the Heisei era.