Twelve-year-old twins Ai and Yu Hayakawa take a mysterious subway to Wonderland to look for their missing scientist parents. Wonderland is a hostile place, ruled by the petulant Earl Tyrant and his assorted henchcreatures. Ai and Yu are attacked by monsters and saved first by Lisa, a practitioner of the "Kigen Arts", then repeatedly by the taciturn, gun-totting Kaze.