He is also likely the boy shown in Danganronpa/Zero who beat another boy, most likely Shōji Yokō, to death with a chair. He was then ambushed by another council member, most likely Asukasei Hino, being blinded by glass shards in his eyes before eventually being killed by an unspecified female Student Council member, possibly Suzuko Kashiki, wielding a cleaver.
Daiki's features are slightly more stylized than his fellow Student Council members, with a squarish face, greenish-gray hair, and very dark brown eyes that seem to have little to no sclerae. He wears the standard uniform of Hope's Peak Academy.
Daiki is shown to be worried about the killing game but still tries to calm everyone else down. He also seems to be level-headed and logical; in the dub, he first tried to see if the remaining Student Council members could make a run for it, believing the odds of them all dying to be slim.
Along with the rest of the student council, Daiki came to a classroom on the fifth floor of Hope's Peak Academy after being shown threatening videos by Junko Enoshima. When the Ultimate Fashionista tells them to kill each other, he and the rest of the council show extreme reluctance, even when the vice president, Kotomi Ikuta, was murdered in front of them by Mukuro Ikusaba. However, Karen Kisaragi's murder of Ryota kickstarted the events of the The Tragedy of Hope's Peak Academy, driving Daiki and his friends to turn on each other.
Daiki was murdered off-screen during the killing game.
During the Tragedy of Hope's Peak Academy, a boy (likely Daiki) is shown beating another boy (likely Shoji) to death with a chair. However, he was ambushed by another student council member, most likely Asukasei, which led to him getting glass shards in his eyes. The blinded Daiki is eventually killed by an unspecified female Student Council member, possibly Suzuko Kashiki, with a cleaver.
- His given name, "Daiki" (大器) means "Great Vessel", a person of outstanding talents who can accomplish a great cause.
- His last name, "Kubo" (久保) means "for a long time" (久) and "protect" (保).
- In Danganronpa/Zero, a boy (presumably Daiki) claims he killed two students before killing another one. However, this does not match the killing order seen in Danganronpa 3. It is possible that he only injured them, believing he killed them.