Mitsugu Sakai is a founding member of the Wild Seven, the terrorist group led by Shuya Nanahara that declares war on the adult-run Japanese government in Battle Royale II: Requiem. His background is marked by personal tragedy: he participated in a resistance effort with his family but lost both parents in the fighting. This loss left him emotionally adrift, and he found a psychological anchor in Shuya, whom he latched onto and ultimately forced his way into joining the Wild Seven. Within the group, Sakai is recognized as the mediator and peacemaker among the members, suggesting a temperament that sought to keep internal conflicts from boiling over. It is possible that he was a previous winner of the Battle Royale program, which would account for his combat capability and his place in the organization. During the assault on the Wild Seven island, Sakai initially opened fire on the incoming class of students but stopped when fellow Wild Seven member Saki Sakurai noticed that the students were wearing explosive collars, revealing their coerced participation. As the final battle against the Anti-Terrorist Attack Team reached its climax, Sakai chose to stay behind and fight in order to buy time for the children and surviving students to escape. Armed with an AK-47, he fought alongside Takuma Aoi, Masami Shibaki, and Osamu Kasai. He was fatally shot in the engagement, and with his last words he told Shuya Nanahara to never stop fighting. His death was part of a suicide bombing that also claimed the lives of his comrades, a final act of sacrifice that underscored his commitment to the cause and to Shuya. In terms of notable abilities, Sakai is portrayed as a capable combatant with proficiency in firearms, and his role as peacemaker indicates strong interpersonal skills that helped maintain cohesion within the Wild Seven. His emotional development traces a path from a traumatized survivor clinging to Shuya for stability to a resolute fighter who willingly gave his life for the group's mission and for the younger generation caught in the conflict.