Cerberos

Cerberos is aggressive, intelligent and voraciously hungry. Food is the simplest way to secure his cooperation, and Hiruma repeatedly uses that appetite to direct him toward whatever unfortunate target needs to be chased.

He is unusually perceptive for a dog. Cerberos can follow complicated situations, track people and participate in Hiruma's schemes rather than behaving as an ordinary pet.

His aggression also establishes a natural affinity with Hiruma. Both intimidate Deimon's players into action, although Cerberos is generally easier to negotiate with because food provides a reliable incentive.

Cerberos possesses exaggerated strength for a dog, including a recorded 120 kg bench press. He can overpower larger dogs and force them into submission.

His tracking ability makes him useful when Hiruma needs to locate missing players. His speed and aggression also turn him into a highly effective training threat: athletes run harder when failure means being chased by Cerberos.

He can stand and move on his hind legs in several comedic appearances, reinforcing the intentionally exaggerated intelligence and physicality given to him.

Cerberos appears throughout Deimon's training and everyday activities as both mascot and enforcement mechanism. Hiruma deploys him whenever intimidation is more convenient than persuasion.

He is also used in schemes surrounding Sena's secret identity. By incorporating Cerberos into staged situations, Hiruma can help create misleading evidence about Sena's whereabouts while Eyeshield 21 is playing.

The manga and anime give different versions of his first association with Hiruma. The anime depicts Cerberos arriving at the football field and challenging Hiruma before Hiruma manages to fasten a spiked collar around him.

Youichi Hiruma is the person Cerberos follows most closely. Although their relationship resembles ownership, supplementary material jokes that Cerberos stays with Youichi Hiruma primarily because he is an easy source of food.

Ryokan Kurita knows Cerberos from Deimon's early days and recounts the anime version of how the dog became associated with the team.

Sena Kobayakawa is frequently terrified of Cerberos and can become one of his targets during Hiruma's training schemes.