The Transverse Tunnel consists of a long corridor behind a one of the monolithic stone statues in Rumille Plain. When presented with a Miniature Statue, a hidden door reveals the tunnel.
Upon his defeat the Chairman Evil King offers the party the Miniature Statue in exchange for his safety. He claims that the tunnel is used to supply materials and workers to Evil Kings from the "Outside World," though he never used it himself. The party plans to go with the intention of staking it out to find other Evil Kings. However as soon as they exit into Pospos Snowfield they meet not only Big Bull Evil King, but Phantom Evil King as well.