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Mondo Owada is a character from Danganronpa: Trigger Happy Havoc, and the culprit Chapter 2. He was the second leader of the largest biker gang in Japan, The Crazy Diamonds, after his brother Daiya, who he had gotten killed in a street racing accident.
After Chihiro, another student who was thought to be female, revealed to him that he was male and wanted Mondo to help him become emotionally stronger, Mondo snaps and unwittingly kills Chihiro in a fit of blind rage and jealously in the boy's locker room. Mondo kept the truth of Daiya's death from the rest of the gang members to honor the "man's promise" the two made to each other for Mondo to keep the gang together, no matter what. This secret was exploited by Monokuma to goad him and the other students into killing each other in Chapter 2, though it's hinted that Monokuma had put pressure on Mondo about his secret beforehand in Chapter 1 when Monokuma gave him a video of the Crazy Diamonds splitting up.