Giboura Massacre

Giboura Massacre also known as The Giboura Junior High Mass Murder Case, is an event featured in ''Danganronpa Gaiden: Killer Killer. ''

It was a mass murder performed by Hope's Peak Academy's Ultimate Soldier, Mukuro Ikusaba who was ordered to do so by her younger twin sister, Junko Enoshima, also known as the True Ultimate Despair.

Prelude
Soon after Mukuro arrived in Japan, Junko who was worried if her older sister's talent as the Ultimate Soldier became obsolete planned to test her talent by creating a mass murder. She picked Giboura Junior High and ordered Mukuro to go on murder rampage.

The Incident
The incident took years before The Tragedy in a Junior High School were Takumi Hijirihara attended school. Takumi became best friends with Shūji Fujigawa during Junior High. Takumi, along with Shūji are one of the students that witnessed murders in junior high school that left him scarred with a disturbed obsession with murder, which he takes out on other killers. They were survivors that got spared and promised that one day he will become the best killer and surpassed the Ultimate Soldier.

While the event turned the shy and timid Takumi into a lover of passionate killings, the massacre also affected Shūji greatly. The Giboura Massacre completely breaks Shūji's calm demeanor, to the point that he turns into a zealot to stop all serial killings.