The Interdimensional Train, also known as the Ghost Train or Subway, is a transportation device utilized by several characters in Final Fantasy: Unlimited. It is one of Cid's inventions, which he names Elizabeth. It is repeated attacked by Omega, in an attempt to retake the fragment that drives the train, and allows it to pass from world to world.
The characters Ai Hayakawa and Yu Hayakawa first sought out the Interdimensional Train as a means to travel to Wonderland, having read an online rumor about a train that appears at an abandoned subway platform at 13 seconds past 12:13 A.M. on the night of a full moon. On board the train, they also met Lisa Pacifist, who was traveling to Wonderland for her own unstated reasons. Throughout the the first 14 episodes of the series, they, later joined by Chobi, used the train to travel to various locations throughout Wonderland. Other characters to ride the train in the series included Kaze and Lou Lupus.
The Interdimensional Train was attacked three times by Omega in the series. The third attack, by Omega's tail, succeeded in destroying the train.
The music "Subway" (地下鉄, chikatetsu?) is played whenever the Train arrives. The ominous theme fits the atmosphere of the Train's appearance, with the intro mimicking the gushing of steam. It is the 21st track in the Final Fantasy: Unlimited - Music Adventure Verse 1, and is composed by Shirō Hamaguchi.
Ghost train refers to a phantom vehicle in the form of a locomotive or train.