Collapse is an ability that allows the user to crumble and destroy their surroundings or objects around them. It is used throughout the anime in Happiness You Did Not Notice (By Ayumi Otosaka) and in Charlotte and Memories to Come (By Yu Otosaka)

The person who is originally known to have this ability is Ayumi Otosaka, whom is Yu Otosaka and Shunsuke Otosaka's younger sister. But that ability is plundered by Yu Otosaka in order to protect her from its dangers.