Sonic

Biodata

Feature	Details
Name	Sonic (索尼克)
Alias(es)	Speed-o'-Sound Sonic; Black Flash
Gender	Male
Affiliation	Hero Association; Ashura Maru
Occupation/Role	Assassin and bodyguard; blade wielder; S-Class hero
Status	Alive 171
First Appearance	Chapter 121
Hero Rank	S-Class Rank 15 upon promotion; later S-Class Rank 1 148 171

Power Progression

Stage / Realm / Level	Chapter	Notes
Ashura Maru’s second blade wielder	120	Ashura Maru binds Sonic as his second recognized wielder, allowing the sword to strengthen Sonic through slain powerful opponents. 120 123
Thousand Blades	125	Unlocks the ability to split Ashura Maru into countless controllable fragments after killing the Demon-level Kelp Monster. 125
Mid-Dragon level	129	Reaches approximately mid-Dragon level after killing over twenty Demon-level monsters in under two weeks. 129
Above Dragon level	134	Ashura Maru lends Demon Power, manifesting purple armor, a demon mask, and a ring behind Sonic; Ashura Maru deliberately withholds fuller transformations. 134
Upper Dragon level	137	The Demon Power gained from the Heavenly Ninja Party raises his physical strength from mid-Dragon to upper Dragon, nearing the peak. 137
Dragon Summit	147	Activates One-Sword Asura and Demon Lord Possession against the Underworld King; after the King’s death, Sonic retains Dragon Summit strength even after the temporary abilities end. 147
Above Dragon level	157	Ashura Maru’s enhancement pushes Sonic beyond Dragon Summit during his battle with Void Foyd. 157
Above Dragon level (permanent breakthrough)	162	Foyd’s death supplies enough Demon Power to break Sonic’s remaining shackle; he remains dissatisfied because Saitama is still beyond him. 162
God Level	164	Reaches God Level through maximum-output Demonification, One-Sword Asura, and Demon Lord Possession while invading the Monster Association. 164
God Level	168	Ashura Maru grants Sonic Demonification, One-Sword Asura, and Demon Lord Possession at maximum power for a fifteen-minute battle against Boros. 168
Complete Ashura Maru power	170	After Satoru relinquishes his share, Sonic sounds the Golden Horn and gains a winged demonic form; his body can sustain it for less than five minutes. 170
God Level	171	Re-enters God Level ten years later, though another challenge against Saitama ends in defeat. 171

Background / History

Ashura Maru selects Sonic as his second blade wielder after the system approves the binding request and deducts 10,000 Emotion Points. The bond gives Ashura Maru a perspective on Sonic’s actions and makes Sonic capable of receiving Nourishment from slain powerful opponents. 120 123

While employed as Zenier’s bodyguard, Sonic intercepts Hammerhead and the Paradise Group. He kills the group at speeds they cannot perceive, then decapitates Hammerhead; the criminal’s negative emotions generate Emotion Points and Demon Power for Ashura Maru. 121 122

Sonic mistakes Saitama for a Paradise Group member and attacks him. Saitama effortlessly tracks his supersonic movement, defeats him with a counterattack, and leaves Sonic badly injured. Rather than abandon his pride, Sonic declares Saitama his target and vows to kill him in their next encounter. 122 123

Ashura Maru subsequently reveals the blade’s purpose: it can absorb a portion of the power of strong enemies Sonic kills and use it to nourish his body. Sonic chooses to hunt monsters rather than people, both for stronger Nourishment and to avoid attracting attention. 123

His monster-hunting campaign brings him into repeated conflict with the Monster Association, the Heavenly Ninja Party, the Machine God Organization, Tsukuyomi, and the Moon Reader Organization. He rejects Monster Cells and refuses to become a monster, insisting on relying on his own combat ability and Ashura Maru instead. 131 133 136 152

After defeating the Underworld King, Sonic receives official recognition from the Hero Association as S-Class Rank 15 under the hero name Black Flash. He treats the rank and two-billion-yen reward chiefly as new ways to provoke Saitama. 148

During the Boros invasion, Sonic receives Ashura Maru’s complete power after Satoru Suzuki voluntarily surrenders his own claim. Sonic defeats Boros after an extended battle, later becoming S-Class Rank 1 following Bang’s retirement. 170 171

Appearance

Sonic is a ninja combatant who commonly carries Ashura Maru and conceals himself with a mask or combat gear. When granted Demon Power, his appearance changes dramatically. 122 134

• Purple, form-fitting demon armor and a demon mask manifest during Ashura Maru’s enhancement. 134
• A purple ring or wheel appears behind him in empowered forms. 134 170
• Maximum Demonification produces purple facial markings, purple eyes, and demon horns. 164
• Ashura Maru’s complete-power form gives him restored armor, black wings, black eyes with golden pupils, and the purple wheel between his wings. 170

Personality

Sonic is intensely proud, competitive, and obsessed with surpassing Saitama. Even humiliating defeats do not discourage him; they instead become motivation to train, hunt stronger opponents, and test new techniques. 123 125 129

He is ruthless toward enemies. Sonic decapitates Paradise Group members, monsters, hostile ninjas, and blade hunters without hesitation, and he keeps track of organizations that target Ashura Maru so he can retaliate later. 122 152

Despite this brutality, he refuses Monster Association recruitment and rejects Monster Cells, viewing monsterization as dependence on borrowed power and an unacceptable loss of human identity. 131 133

Sonic is tactical beneath his arrogance. He uses blade fragments as hidden teleportation marks, intentionally lures Monster Association reinforcements to him, and retreats when faced with opponents beyond his present ability. 132 134 162

His relationship with Ashura Maru evolves from mutual exploitation into fierce loyalty. He reacts angrily when opponents insult the blade and increasingly accepts Ashura Maru’s strategic judgment, though their conversations remain confrontational and sarcastic. 129 134

Abilities & Skills

Ninja Speed and Assassination

Sonic’s core fighting style is high-speed, lethal close-quarters combat.

• Moved too quickly for Paradise Group members and Hammerhead to see before decapitating them. 122
• Claims to have surpassed the speed of sound during his first clash with Saitama. 122
• Uses stealth, smoke shuriken, surprise attacks, and precise decapitation as standard assassination methods. 123 132
• His speed eventually allows him to bypass Genos and fight across city blocks against Void Foyd. 148 157

Ashura Maru Nourishment

Ashura Maru converts the negative emotions and Demon Power of slain strong enemies into growth for Sonic.

• Sonic receives a share of acquired Demon Power as bodily Nourishment. 122 125
• Stronger monsters yield significantly greater returns, making monster hunting central to his growth. 125 129
• Robots provide no Nourishment because they lack usable emotion or energy. 137
• Excessive borrowed Demon Power risks turning Sonic into a demon driven solely by slaughter. 133

Thousand Blades and Fragment Control

Ashura Maru can shatter into numerous fragments without ceasing to function.

• Sonic telekinetically controls the fragments and reforms them into a sword. 125
• Fragments remain linked by purple energy even after the blade is shattered. 129
• He can embed fragments in an opponent’s body to attack internally or establish teleportation points. 131 132
• The fragments can release black slashes independently and are durable enough to resist attacks from Gouketsu and Nyan. 134

Flying Thunder God

Sonic teleports between Ashura Maru fragments or pre-established marks.

• Lets him evade attacks that would otherwise kill him, including Saitama’s punch. 131
• Allows rapid surprise attacks around opponents, including Gouketsu and the Underworld King. 134 146
• He secretly marked Void Foyd, then used the mark to pursue and execute him after the Ninja King escaped. 162
• Can redirect a catastrophic attack by teleporting it through a mark placed on an enemy. 165

Breathing Styles

Sonic learns and develops sword techniques built around Breathing Styles.

• Thunder Breathing — Taught by Ashura Maru to develop Sonic’s technical skill rather than relying only on slaughter. 134
• Dark Breathing — Sonic’s original style, created through wilderness training. 135
• Four-Shadow Burial — Produces shadow-like blade attacks; used against Ancient King, the Underworld King, and the Heavenly Ninja Party. 135 146 156
• Great Black Heaven — An advanced Dark Breathing attack that engulfs the battlefield in overwhelming darkness. 147 169
• Ten Shadow Burial — A high-level Dark Breathing technique used against Boros and Void Foyd. 157 169
• One-Sword Rakshasa — Combines all ten forms of Dark Breathing into a decisive strike. 147 170

Lightning Techniques

Through Legendary Buff Sharing, Ashura Maru grants Sonic lightning-based abilities.

• Chidori — Shared directly by Ashura Maru after the system unlocks Legendary Buff Sharing. 135
• Chidori Sharp Spear — A ranged lightning blade capable of splitting a massive ancient tree and piercing multiple enemies. 136 137
• Kirin — Summons a massive lightning beast from storm clouds; it annihilates Machine God robots and Heavenly Ninjas across a mountain battlefield. 136 137

Demonification and Complete Power

Ashura Maru can temporarily elevate Sonic through increasingly dangerous transformations.

• Demon Lord Possession and One-Sword Asura — Used to break through Sonic’s limits during major battles. 147 157
• Maximum-output Demonification — Raises Sonic to God Level but consumes Demon Power at an extreme rate. 164
• Domain Expansion: Ashura Kannon — Creates a giant sword and countless summoned blade constructs that can replicate powerful opponents. 168
• Holy spear — In complete-power form, Sonic wields a white spear that turns what it touches into salt. 170
• Limit — His complete Ashura Maru transformation lasts less than five minutes because his body cannot sustain the power longer. 170

Equipment / Weapons / Items

• Ashura Maru — Sentient demon blade and Sonic’s primary weapon, power source, adviser, and fragment-based teleportation medium. 120 123
• Shuriken — Includes smoke-producing shuriken for escape and enhanced explosive shuriken used against Genos. 123 130
• Flying Thunder God marks — Marks or blade fragments placed in advance as teleportation anchors. 146 162
• Golden Horn — Spiritual-realm artifact Sonic blows to unlock Ashura Maru’s complete power. 170

Relationships

• Ashura Maru — Sonic’s sentient blade, mentor, power source, and tactical partner. Their partnership is hostile in tone but built on growing trust and fierce loyalty. 123 129 134
• Saitama — Sonic’s self-declared archenemy. Sonic repeatedly seeks to surpass him through strength, hero rank, wealth, games, and food-related provocations. 123 148 156
• Satoru Suzuki / Unlicensed Rider — Fellow blade wielder and eventual rival for Ashura Maru’s complete power. Sonic spares Satoru after he refuses to submit, while Satoru later relinquishes his share of Ashura Maru’s power so Sonic can fight Boros. 145 147 170
• Genos — Saitama’s disciple and a recurring obstacle to Sonic. Their encounters are marked by mutual insults and destructive combat. 130 148 150
• Gale Wind and Hellfire Flame — Former ninja-class associates who try to recruit Sonic into the Monster Association; Sonic rejects them and kills them. 131 132
• Void Foyd / Floyd — Ninja King and Above Dragon-level opponent who tests Sonic using illusions and the Gateway. Sonic ultimately tracks and kills him. 157 162
• Boros — Cosmic overlord who becomes Sonic’s greatest battle opponent. Boros respects Sonic’s power and twice invites him to join the Dark Matter Pirates. 168 169
• Hero Association — Officially recognizes Sonic as Black Flash and promotes him to S-Class, but later tensions arise when it requests access to Ashura Maru. 148 150

Story Role / Major Arcs

Paradise Group Incident

Hired by Zenier, Sonic eliminates Paradise Group members and Hammerhead, then encounters Saitama for the first time. The defeat establishes his overriding desire to become stronger. 121 122 123

Monster-Hunting Campaign

After learning Ashura Maru’s Nourishment mechanic, Sonic enters Z City’s uninhabited zone and kills increasingly powerful monsters. He unlocks Thousand Blades, defeats the Kelp Monster and Awakened Cockroach, and climbs into Dragon-level power. 124 125 129

Monster Association Conflict

Sonic rejects recruitment by monsterized former ninja associates, defeats Nyan and severely wounds Gouketsu, then withdraws when multiple Dragon-level executives converge on him. He later destroys Heavenly Ninjas, Machine God forces, and hostile blade-seeking organizations. 131 134 137 152 156

Underworld Abyss Incident

Sonic fights the Underworld King Puru Pig inside the Underworld Abyss, where his existing marks and blade fragments prevent the King’s dimensional ability from suppressing Flying Thunder God. He kills the King, reaches Dragon Summit, and formally becomes Satoru’s rival for Ashura Maru’s full power. 145 146 147

Ninja King Battle

Void Foyd challenges Sonic to determine whether he is worthy of Ashura Maru and God. Sonic survives Foyd’s Gateway illusion, defeats him through hidden teleportation marks, and permanently advances to Above Dragon level. 157 162

Monster Association Raid

Sonic invades the Monster Association’s underground base, overwhelms its forces, and kills Monster King Orochi by redirecting the Gaia Cannon through a Flying Thunder God mark. 163 164 165

Cosmic Overlord Arc

Sonic kills the Sky King and Melzargard before entering Boros’s ship alone. With Ashura Maru’s full power granted through Satoru’s sacrifice, Sonic defeats Boros in a battle that leaves both fighters devastated. 167 168 169 170

Notable Quotes

“Saitama, the next time we meet will be the day you die! I, Sonic of Speed, will definitely take you down!” 123

“Become ugly freaks like you? I don't need that!” 133

“The man who will kill you!” 145

“You're very strong, but compared to Saitama, you're not worth mentioning!” 169

Trivia

• Sonic’s official hero name, Black Flash, reflects the black-light streaks witnesses see when he moves at high speed. 148 152
• He received two billion yen for eliminating the Dragon-level Underworld King disaster. 148
• Sonic deliberately provokes Saitama because Saitama’s irritation generates unusually large amounts of Emotion Points for Ashura Maru. 148 150 156
• He refuses to use Monster Cells even when critically injured and offered greater strength by Gouketsu. 133
• Ten years after the Boros battle, Sonic destroys the Machine God Organization and Moon Reader Organization, while monsters flee populated areas to avoid him. 171