Speed-o'-Sound Sonic, usually called simply Sonic, was born and trained in the Hidden Ninja Village from birth, graduating as part of the 44th Graduation Class alongside fellow ninja Flashy Flash — a class nicknamed "The End." He first appears in the story as a mercenary bodyguard hired by the wealthy Zeniru, using his ninjutsu, katana, and explosive throwing weapons to devastating effect against anyone who threatens his employer.
After crossing paths with Saitama and losing, Sonic became fixated on him as his eternal rival, repeatedly seeking him out for rematches he refuses to give up on. His signature technique, Four Shadows Burial, lets him move fast enough to leave four simultaneous afterimages, making him one of the quickest fighters in the series outside of S-Class.
A slender young man with a lithe, almost feminine build and sharp, avian features, long black hair in a high messy topknot, and two purple semi-circular marks under his eyes marking him as a master ninja. Wears a tattered black skintight bodysuit with metal plating on the shins, forearms, and chest, plus a long flowing purple scarf.
Narcissistic, obsessive, and openly bloodthirsty, prone to manic smiling when his combat "bad habits" kick in. Fixated above all else on defeating Saitama, secondary to being recognized as the fastest being alive. Incredibly mentally resilient — he never lets defeat break him, only fuels further training — though his ego routinely leads him to underestimate opponents.
Born and raised in the isolated Ninja Village, part of "Team 5" alongside the prodigy Flashy Flash, whom he was the only person able to talk to as a child despite being the "hard worker" next to Flash’s genius. Survived the "Final 44" graduation massacre, after which the Village’s founder was put into hibernation following a fight with Blast. Became an independent mercenary after the Village’s collapse.
Hired by billionaire Zeniru to eliminate the Paradisers, he mistakes bald Saitama for one of them and attacks — only to be accidentally, humiliatingly neutralized by a groin strike, sparking his lifelong obsession with beating him. Escapes prison to duel the Deep Sea King, loses his weapons and clothes when rain boosts the King’s power. Fights Genos to a standstill near Saitama’s apartment until Saitama personally intervenes. Later tries to eat a Monster Cell to gain power but cooks it first out of habit, neutralizing the transformation and giving himself severe diarrhea instead. During the Ninja Village arc, reunites with Flashy Flash, reveals he was only pretending to serve the "Heavenly Ninja Party," and helps wipe them out; the pair then resist the resurrected Village founder Empty Void’s temptation with “God’s” power and are saved by Blast. By series present, has officially lost to Saitama 14 times.
Superhuman Speed: subsonic movement generating sonic booms and multiple afterimages, eventually fast enough to trade blows with Flashy Flash. Ten Shadows Burial / Four Shadows Burial: afterimage-based overwhelm techniques. Wind Blade Kick: a high-velocity aerial kick. Weaponry: a ninjato sword, exploding shuriken, and homing shuriken. Weakness: his obsession with flashy speed leaves him open to simple, efficient counters from truly "limitless" opponents.
vs. Saitama (First Meeting) — Ch. 13–15
Tried to use his speed to intimidate Saitama. Saitama neutralized him with an accidental groin strike — the humiliation that became the core obsession driving Sonic's entire arc.
vs. Deep Sea King — Ch. 25
Speed against regeneration. Sonic pulled out once the rain made the King too dangerous to keep pressing — still proof he could outrun a Disaster Level: Demon threat.
vs. Genos — Ch. 44
Speedster cyborg vs. speedster ninja. Saitama broke it up before it could escalate, but it put Sonic on the map as a match for top-tier S-Class speed.
vs. Flashy Flash — Ch. 196–198
A reunion duel with his childhood friend at their old hideout. Ended in a draw — Flash admitted Sonic had gotten "strong" enough that he'd need his absolute techniques just to keep pace.
Major: Ch. 12–15, 25, 44, 78, 191–200. Minor: Ch. 21, 31, 32, 33, 37, 43, 89, 95, 172. Mentioned only: Ch. 38, 92, 122.
Saitama: his self-declared eternal rival, though Saitama mostly sees him as an annoying stalker. Flashy Flash: his only true childhood friend, sharing a coordinated, deeply loyal bond despite constant bickering. Genos: mutual contempt — Genos calls him a freak/pest, Sonic dismisses him as a "small fry." Puri-Puri Prisoner: a former cellmate who affectionately (and unwantedly) calls him "Sonic Honey."
“I am Speed-o’-Sound Sonic! I am an amazing ninja who contracts for everything from assassinations to serving as a bodyguard!”
“Saitama! Next time we meet, you’re a goner!”
Genos once pointed out his name is "redundantly repetitive" (Speed/Sonic and Sound/Sonic both implying the same thing). The only character shown cooking a Monster Cell before eating it, neutralizing its power and giving himself digestive distress instead.
🇯🇵 Japanese Voice Actors
Kaji, Yuuki
🇯🇵 Japanese
🇺🇸 English Voice Actors
Kimerer, Erik
🇺🇸 English