A member of Hope's Peak Academy's Student Council. She and the rest of the council were forced into a killing game by Junko Enoshima and Mukuro Ikusaba, an event that would later become known as the The Tragedy of Hope's Peak Academy.
~!When the Killing Game began, Tsubasa and Tarou Kurosaki fled into the hallway. They decided to commit a double suicide and each held a gun to the other's chin. But before they could pull the trigger, Sousuke stabbed Tarou from behind, who fell on Tsubasa, ultimately trapping her. Sousuke then pounded the sharp weapon through Tarou's body and into Tsubasa's using a shovel. Tsubasa screamed and begged for him to stop, but Sousuke continued to drive the object deeper into Tsubasa until she died.!~
(Source: Danganronpa Wiki, edited)