Hiyama Kazuki

Lost his younger brother 16 years ago in the Great Rokumei City Arson.
He supported the mental side of Sirius as Watase's right hand man, calming down the brash Dojima with his prudent disposition and keeping Kazami in check when she was an overeager newcomer.
When he learned the truth about the Great Arson, he was somewhat hesitant, but still agreed with Watase's LABO terrorist attack plot. He became a member of Q alongside Dojima and participated in the terrorist attack, but when he tried to get Subject N out of LABO, he bumped into Kuroda and Higa. After Higa broke Hiyama's legs, the rescue worker/terrorist still tried to escape, but he ran out of strength and got caught in a fire, leaving behind a tragic corpse.