Reiji Kiriya

, otherwise known as Viper, he is a vicious thug who is at the centre of Oga and Miki's story. His cunning and thirst for revenge gain him the leadership of Teimou's Academy skinheads, who are driven by him to take St. Ishiyama hostage in order to get back at Oga. He wears the hair in black power style and his face has three vertical scars carved by Oga using Kiriya's own nails, in retribution for his attack on Miki.

His plan for revenge ultimately backfires when the Red Tails and the Six Knights capture his underlings and Oga and Miki defeat Teimou's shadow group (see below). After being badly injured by Oga's Zebub Blast, he hallucinates and takes Oga himself for a devil, and crawls away in mortal fear.