The Graveyard at the Bottom of Gravity - Part 1 - S1.E7

The 999 falls into the Sargasso, where they find the remains of the 333, a missing train. Traveling aboard, Tetsuro, Maetel and the Conductor find only skeletons. A woman aboard the train, Ryuzu, reveals herself, saying that she sped up time on the train which killed everyone. Through her threats, she takes a hold of Tetsuro and departs the train's remains with him.