Zenji is the most powerful Mafia boss under the Ten Dons. He is jealous of Light Nostrade's quick rise through the ranks and very hostile towards him, going as far as punching Light in the face when the latter snubs him in front of other Mafia members in a gathering of the Mafia and some hired assassins in the Cemetery Building on September 3 2000.
Later on the same night, when Kurapika follows Light's order to bid for a pair of Scarlet Eyes for his daughter Neon in the Mafia's rescheduled underground auction, Zenji keeps raising the bid in order to sabotage his plan. Kurapika ends up winning at the price of 2.9 billion Jenny, much more than Light expected. Angered, Zenji finds Kurapika outside the building when the auction is over and threatens to kill him with a gun. However, Kurapika, who is in a state of agitation after seeing the stolen eyes of his people, activates his scarlet eyes and unleashes his aura, paralyzing Zenji for a moment.