Onsoku no Sonic

Sonic is proud, competitive, bloodthirsty, and obsessed with proving the superiority of his speed. He normally carries himself with a calm confidence, but encounters with sufficiently strong opponents produce an excited smile that he recognizes as one of his own bad habits.

His rivalry with Saitama quickly becomes the central fixation of his life. Every defeat convinces Sonic that he simply needs another training method or technique rather than forcing him to accept the enormous difference between them.

He is also fiercely independent. Sonic has little respect for heroes, monsters, criminal organizations, or former ninja institutions and resists attempts by stronger groups to recruit or control him.

Sonic is an elite ninja whose defining ability is extraordinary speed. He can produce afterimages, move faster than most opponents can visually track, leap across buildings, and change direction in midair with remarkable agility.

He uses ninjutsu techniques such as explosive shuriken, substitution tactics, concealed weapons, and rapid sword attacks. His Ten Shadows Burial creates multiple afterimages through sheer movement speed, while later training allows him to increase that number further.

Sonic is also highly skilled with a ninjatō and throwing weapons. His physical conditioning gives him substantial endurance despite his slim build.

Later manga developments reveal that Sonic graduated from the Ninja Village's 44th class alongside Flashy Flash. Their shared upbringing under the Village's brutal training system helps explain Sonic's extraordinary ability and his hatred of being controlled.

Sonic first appears as the bodyguard of Zeniru, attacking the Paradisers after they threaten his employer. He mistakes Saitama for one of the criminals and challenges him, only to suffer an immediate and humiliating defeat.

From then on, Sonic repeatedly seeks Saitama out. He trains specifically to surpass him, interferes in other conflicts when Saitama is involved, and occasionally crosses paths with Genos.

During the Monster Association's recruitment campaign, Gale Wind and Hellfire Flame offer Sonic monster cells and promise him dramatically greater power.

Sonic cooks the monster cell before eating it, unknowingly destroying its transformative effect and remaining human.

Later, his history with Flashy Flash and the Ninja Village draws him into a wider conflict involving surviving ninjas and their former master.

Saitama is Sonic's self-declared eternal rival. Sonic interprets every effortless defeat as motivation for another rematch, while Saitama rarely treats the rivalry seriously.

Genos becomes a recurring opponent when Sonic's pursuit of Saitama brings him into conflict with Saitama's disciple.

Flashy Flash was Sonic's classmate in the Ninja Village. Their shared childhood and differing responses to the Village's cruelty create a complicated mixture of rivalry and familiarity.

Gale Wind and Hellfire Flame are senior ninja acquaintances who try to recruit Sonic into the Monster Association.

Zeniru employs Sonic as a bodyguard when he first enters the story.