Mari-chan is a sweet, brave six-year-old who loves to play with her best friend, a magical stuffed bunny named Roboto Bunny. When her rock-climbing dad goes missing in an avalanche in faraway Antarctica, Mari-chan is heartbroken-until Roboto Bunny reveals a secret passage in her closet that leads to a tunnel to the Underworld and a magic tree with doors that can take her anywhere...even to Daddy. But there's a catch: the tunnels are too small for a big girl, so Mari-chan is turned into a baby to fit!On their journey, baby Mari-chan and Roboto Bunny must outwit hungry animals, alligator bridges, three-headed "beasts," silly thieves, grumpy talking trees, a Bunny Kingdom gate test, and a wise owl tribunal. Along the way, Mari-chan discovers that even in a tiny body, her courage, creativity, and kindness are bigger than she ever imagined. But will her bravery and wits help rescue her dad, before it's too late? It's up to Mari-chan and Roboto Bunny to find out.This heartwarming and imaginative allegory, reminiscent of Dante's Inferno, shares that a difficult journey often has the best destination.