Blue Exorcist

Mephisto's amusement park is haunting by the ghost of a child, so the Exwires are tasked to look him, splitting up in pairs. While searching for the ghost, Rin uses this opportunity to ask Shiemi out on a date to the amusement park sometime later. Rin and Shiemi find the ghost at a carousel, and although the ghost appears to be sad, he instead is quite a mischievous one. While Shiemi chases the ghost around, Rin encounters Amaimon, his younger half-brother, who steals Kurikara and forces him to fight in a roller coaster. Rin goes haywire, throwing two steel beams at Amaimon, who dodges them. The steel beams pierce through a ball pit containing Shiemi and the ghost inside, but Rin manages to blast the steel beams away to save them. The ghost, before disappearing, thanks Shiemi for playing with him. When Amaimon has Rin on the ground, one of the Exwires comes to defend him, causing Amaimon to retreat. As Yukio meets up with Rin and Shiemi, the Exwire exposes herself to be Shura Kirigakure. (Source: Wikipedia)