Toradora!

Ryuuji and Taiga stay up all night, still unsure of what had occurred the night before, and discuss how to scare Minori. Yuusaku overhears them and wants to help, believing that Minori loves being terrified, and enlists Ami in helping too. They decide to pull a massive scare by taking a walk through a hidden cave filled with traps designed to scare Minori; however, Ami backs out after Ryuuji refuses to tell her why he wants to do this; however, she eventually decides to help, and leads the group into the cave, where Yuusaku has planted many pathetic scary traps. Ami splits with the group by going to another pathway, and Ryuuji follows her. While alone, Ami tells Ryuuji that she is better suited for him. The situation quickly gets out of hand as Yuusaku and Minori disappear, and the mysterious hair and seaweed from last night appears again. It is later revealed that Yuusaku and Minori were playing a trick on them, which included last night's scare. The two claim to have known what Ryuuji and Taiga were up to, but Minori appreciates it for being so thrilling. (Source: Wikipedia)