Soul Train

The Soul Train (ソウル・トレイン, Sōru Torei) was a sort of Oversoul that appeared at the end of the final battle within the Great Spirit.

About
The Soul Train is a modern locomotive hauling both passenger and freight cars. Johann Faust VIII and his wife Eliza Faust acted as its conductors. The family and friends of the Five Elemental Warriors were seated in the passenger cars and Hao's followers and other teams who participated sat in the freight cars.

After Asakura Hao created a Black Hole within the Great Spirit, the Soul Train appeared and Oyamada Manta, together with Umemiya Ryunosuke, appeared out of the window of the locomotive and grabbed the Five Elemental Warriors to stop them from falling into oblivion. Together with the X-Laws and the Archangels, it was used to anchor everyone within the Great Spirit, until Opacho's self-sacrifice forced Hao to close the Black Hole before it swallowed her.

Anime/Manga Difference
Due to major changes in the storyline, the Soul Train never appeared in the anime series.

Trivia

 * It is based on a freight rail transport, though it also has passenger cars.