|“||If that pathetic monster beats you, you'll have to find a new Buddy! Heh heh heh... just kidding.||”|
—Armorknight Cerberus "A"
|“||I'll devour anyone who gets in the way! Tyrant Bites!||”|
Armorknight Cerberus is Rouga Aragami's real buddy monster.
Cerberus is a white 3-headed dog wearing heavy armory and weaponry, each head has unique traits. Cerberus's center head acts like a "boss" and is the only one that talks. When Cerberus talks, he refers to himself in plural.
As of Triple D, his fur became jet black and his weapons have doned the black color with orange highlights.
Cerberus is shown to be rather aggressive and enjoys fighting, he can also acknowledge an opponent's potential.
He is very loyal to Rouga and genuinely cares about him as a friend, staying hidden from view before Rouga revealed himself to be "Wolf" and always being very willing to work with him. He also joked about Rouga enjoying his fight with Gao which was unusual for him and showed some concern over him during Rouga's fight with Shosetsu.
His ability to fuse with Rouga's Items as Cerberus A in a way represents their bond, as when activated the two are essentially fighting as one. Many Danger World cards feature Rouga and Cerberus together and some of their card flavors also show hints about their bond.
Cerberus first appeared when Rouga called him to prepare to attack a nearby Photon Metal mine while disguising himself as "Wolf". Because Rouga needed to keep his identity as Wolf a secret, Cerberus would remain hidden unless called.
Later he returned when Rouga confronted a frustrated Kiri, and they take him to Sengoku Academy. He then fights alongside Rouga during the 5 vs 5 match between Aibo Academy and Sengoku. During Rouga's fight with Gao, Cerberus noticed Rouga is having fun which he joked about.
During the Gaen Cup Cerberus noticed Rouga wasn't focusing on his matches and frequently had to tell him to snap out of whatever was distracting him but still showed genuine concern over him. When Rouga was kicked out of Disaster Cerberus stayed loyal to him and helped him assist Tasuku and Kiri destroy the Portal generator to Darkness Dragon World.
Season 2: Hundred
Season 3: Triple D
At some point before the series, Cerberus evolves into "Tyrant Cerberus". Later, Cerberus come across Bal, and saved him from Doctor Gara. Grateful for this, Bal draws a violent Impact Monster Cerberus, "Violence Gazer" as a thanks. Just a moment after that, Dai Kaido came across Rouga, who is eager to use that card. And the power of "Violence Gazer" is as violent as its name.
Sometime after Gara captured Bal, Gao requested Rouga to help with finding Bal, in which Cerberus convinced him to accept such a request over the fact that Cerberus "owes Bal one".