Spine-chiller! Titan Junior High School - S1.E8

After the race of the last day, Hange and the other upperclassmen challenge Eren's class to a test of courage. That night they arrive at school, where Hange and Levi explain the rules: they must visit the art, music, and science rooms and write their names on the blackboard. The class splits into two groups and head out, encountering various ghostly apparitions said to be the "Seven Wonders of Attack Junior High"; there is a rumor that anyone who sees all seven will be cursed with misfortune. Finally reaching the gym, they find that the ghosts were, in fact, a prank orchestrated by the upperclassmen. Erwin Smith, the club's advisor, reveals that one spirit, the woman with black hair whom Christa encountered, was, in fact, a real ghost.