Warabi is a member of the Hunters.
He is shown to be uncaring and cruel towards individuals that are weaker than him.
While taking blood from Koutetsujou passengers, a man asks that he give blood for him and his wife. Uryuu doesn't mind it, but Warabi wonders whats the fun in that. As he approaches the man, the man offers to give four times the amount of blood, as long as his wife don't need to give and Warabi agrees on the deal, but then proceeds and cuts the man's arm, telling their staff to collect the blood from the floor.
Uryuu tells him that he is tired of seeing him picking on the weak, but Warabi ignores him. Takumi then starts yelling at Warabi and Warabi turns looking at Takumi and commenting that he probably can give 30 times the amount of blood and if he wants to make a deal.