Sirius

Biodata

Feature	Information
Name	Sirius (西留斯)
Alias(es)	Black Wolf Sirius; Calamity Sirius
Species/Race	Human; transmigrator in a young body; Mythical Zoan Devil Fruit user
Gender	Male
Affiliation	Formerly the Beasts Pirates; Captain of the Sirius Pirates
Occupation/Role	Pirate captain; swordsman
Status	Active
First Appearance	Chapter 1
Devil Fruit	Dog-Dog Fruit, Mythical Zoan, Model: Fenrir

Power Progression

Stage / Realm / Level	Chapter	Notes
Mythical Zoan: Giant Wolf	1 3	Acquires the Fenrir Fruit while stranded on a deserted island; gains giant-wolf transformation, fire breath, poison, immense strength, sharp fangs, and the inability to swim.
Giant Wolf, early combat form	7 8	Fights Jack as a roughly four-meter-long wolf; overwhelms him with speed, strength, and fire breath.
Beastman / Werewolf Form	23 33	First reveals his lean, agile human-beast form to Yamato; regards it as a Zoan user’s strongest combat form.
Enlarged Giant Wolf	47	His wolf form grows from roughly four meters to over ten meters long after years of growth and devouring.
Six Powers	167	Learns the Government’s Six Powers alongside Yamato; masters most techniques quickly, while Kami-e requires more time.
Seimei Kikan-enhanced Beast Form	192 193	Uses Seimei Kikan to reshape his wolf body into an upright giant werewolf over one hundred meters tall; gains greater reach and destructive sword power.
Advanced Seimei Kikan and toxin enhancement	290	Compresses his body to boost speed, alters his sword trajectories mid-swing, and enhances his physical functions with toxin for near-instant movement.
Colossal giant werewolf	402	Expands beyond two hundred meters while fighting Charlotte Linlin, causing the ground to sink under his weight.
Black armor combination	435	Black’s armor encases Sirius’s werewolf form, adding jet propulsion and forming the Sirius Pirates’ peak combined combat configuration.
Devil Fruit Awakening	470 471	Severe injuries trigger a berserk Awakening into a black werewolf over one thousand meters tall. Yamato restores his consciousness, leaving him with a more bestial yet humanoid true werewolf form.
Higher-level Haki	479 484 494	Develops beyond conventional Haki through consciousness and merged will with Yamato; later uses black fluctuations that repel Uranus’s wind and lightning.

Background / History

Sirius is a transmigrator from an “azure planet,” with a mature soul inhabiting a child’s body. He spent nearly a year surviving alone on a deserted island, hunting, cooking, and building a stone house. During that time, he ate a spiral-patterned Devil Fruit, discovering that he had entered a world of pirates when the fruit gave him a giant-wolf transformation and took away his ability to swim. 1

Kaido fell from the sky onto Sirius’s island while seeking death. Although Sirius immediately recognized Kaido as a Pirate Emperor and understood their overwhelming difference in strength, he treated the encounter as an opportunity. Kaido identified him as a Mythical Zoan user, took an interest in his abilities, and brought him to Wano. 2 3

Within the Beasts Pirates, Sirius trained under King alongside Yamato, Jack, and Black Maria. He quickly established himself as exceptionally gifted, defeating Jack in their first assessment and developing a close bond with Yamato through training, battles, and their shared desire to see the wider world. 7 8 30 33

After leaving the Beasts Pirates, Sirius formed the Sirius Pirates. He chose to leave the New World for the Four Seas to avoid immediate clashes with the Emperors and Marines, then led his crew toward the North Blue aboard a ship also named the Sirius. His bounty subsequently reached one billion Belly. 141 142 143

Appearance

Sirius initially appears as a young boy, but his body and forms develop drastically as he grows. His Devil Fruit transformations are defined by glossy black fur, wolf features, and an ominous black aura. 7 23 47

• Human form — A child at the start of the story; physically stronger than an ordinary child even before transforming. 30
• Giant Wolf form — A black wolf roughly four meters long in his early Beasts Pirates period, later growing beyond ten meters. 7 47
• Werewolf form — A lean, agile human-beast form with claws and a wolf-like appearance. 23 33
• Seimei Kikan giant werewolf — An upright, ferocious wolf form exceeding one hundred meters in height. 192
• Awakened form — A true werewolf form surrounded by black energy, more wolf-like than his original human-beast state but more humanoid than his altered beast form. 471
• Black armor form — A pitch-black armored werewolf configuration with a glowing chest orb, scattered lights, and jet nozzles. 435

Personality

Sirius is adventurous and intensely curious. Even while isolated on a deserted island, he regarded Kaido’s arrival as an exciting break from monotony; later, he chose to explore nearby planets rather than immediately return to a Blue Sea where Imu awaited him. 1 478

He is pragmatic about power, believing that strength is the most valuable resource on the sea because it can secure wealth and everything else one needs. This outlook drives his decision to trade Heavenly Gold for the Six Powers rather than pursue material gain. 166

Despite his confidence and tendency to joke in dangerous situations, Sirius is protective of his companions. He refuses to needlessly risk their lives, takes responsibility for Jack when they are late, initially refuses to bring Yamato onto a battlefield, and retreats from Zephyr rather than accept casualties among his crew. 7 11 196

Sirius is also notably magnanimous toward defeated or indebted opponents. He spares Golden Lion, gives Kid advice about Haki, and is willing to help Chinjao despite initially refusing the Eight Treasures Navy’s request to join him. 280 300 340

Abilities & Skills

Mythical Zoan: Fenrir

Sirius’s Devil Fruit grants transformations modeled after Fenrir, giving him extraordinary physical power, predatory traits, fire, poison, and growth through devouring. 3 8 9

• Transforms between human, giant-wolf, werewolf, altered giant-werewolf, and Awakened states. 23 192 471
• Possesses strength described as inherited from Fenrir, capable of easily suppressing Ancient Zoan user Jack. 8
• Has enhanced sight, hearing, and smell as a Mythical Zoan user. 34
• Uses fangs capable of biting through stone walls and piercing Kaido’s tough skin. 11 81
• Cannot swim due to being a Devil Fruit user. 1

Devour

Devour is the core ability of Sirius’s Fenrir Fruit: he can consume virtually anything and convert it into nourishment for growth. 9

• Restores stamina and heals injuries after eating. 9
• Allows him to consume solid materials, including stone and bullets. 11 303
• Lets him neutralize toxins by inhaling and digesting them, rendering Zero’s Hydra poison ineffective. 290
• Can consume air and its contained shockwaves, allowing him to swallow the Giants’ energy attack. 448
• Causes an enormous appetite; he can eat several times his body weight in one sitting. 58

Fire and Toxin

Sirius can breathe destructive flames and secrete lethal poison as aspects of his Fenrir ability. 3 7

• Fires concentrated pillars of flame powerful enough to blast through a thick stone wall. 7
• Produces black flames in sword combat. 81
• Uses chemistry knowledge to alter his fire with an additional substance that resists extinguishing. 49
• Can self-administer toxin for temporary boosts to strength and speed. 100 290
• His toxin enhancement can raise his speed to nearly instantaneous levels. 290

Haki

Sirius develops all three major forms of Haki and later seeks a realm beyond conventional mastery. 218 479

• Armament Haki — Uses Internal Destruction Armament Haki to greatly amplify his sword strikes. 218
• Observation Haki — Can assess opponents through their presence and combat ability; recognizes the threat posed by future sight. 217 288
• Conqueror’s Haki — Knocks out a crowd of hostile spacefarers with an invisible burst of willpower. 484
• Merged Haki — Combines his will with Yamato’s to evolve their Haki and empower Black’s mechanical giant. 484
• Higher realm — Uses black fluctuations capable of repelling Uranus’s weather-based attacks. 494

Six Powers and Seimei Kikan

Sirius learns the Government’s Six Powers through a deal with CP0, then turns Seimei Kikan into a key component of his transformation and swordsmanship. 166 167

• Uses Finger Pistol for precise single-target attacks. 217
• Uses Tekkai defensively; Vulture specifically acknowledges its quality. 217
• Uses Kami-e and air-stepping movement in battle. 288
• Reshapes his wolf body into a towering upright giant werewolf. 192
• Compresses his form to increase speed and changes the direction of his limbs and blade mid-attack. 290
• Forms sword-like structures from his own fur through Seimei Kikan. 291

Swordsmanship

Sirius primarily fights with a greatsword, combining enormous physical strength, Haki, transformation abilities, and unconventional wolf-like movement. 34 81

• Wolf Sword Style — A close-range style that combines greatsword strikes with his fangs and predatory mobility. 81
• Vacuum Wave — A powerful slash capable of tearing apart an island and detonating the air. 218
• Great Eruption — A wide-area attack used when precision attacks are insufficient. 217
• Crescent Moon Heaven Slash — The renamed version of his signature slash-wave attack during the battle with Zephyr and the Vice Admirals. 193
• Elbaf Spear: Great Eruption — A stronger technique prepared against Dorry and Brogy. 319
• Hellfire Annihilation — Black flames used to engulf and crush Zero. 290

Equipment / Weapons / Items

• Greatsword — Sirius favors oversized greatswords, which his Fenrir-enhanced strength allows him to wield one-handed. 34
• Unnamed personal sword — Forged when the Sirius Pirates left Wano; it accompanied Sirius for four years before Imu broke it in half. 478
• Black armor — A Black-created combat suit that encases Sirius’s werewolf form and provides jet propulsion. 435
• The Sirius — His crew’s ship and later a transforming, AI-controlled vessel linked to Black. 143 275 281

Relationships

• Yamato — Closest companion, longtime training rival, and girlfriend. They grew up together under Kaido, fight side by side, merge their Haki, and Yamato is able to call Sirius back from his berserk Awakening. 11 33 471 484
• Kaido — Former captain and teacher. Kaido recruited Sirius after recognizing his Mythical Zoan potential; their later reunion becomes a confrontation between former mentor and student. 2 3 404
• King — Sirius’s stern trainer in the Beasts Pirates. King pushes him through severe physical training and evaluates his growth through combat. 7 30 33
• Jack — A close, brother-like friend from the Beasts Pirates. Sirius protects him from blame, while Jack consistently trusts Sirius’s strength and judgment. 7 143 178
• Black Maria — Childhood companion and crewmate. She supports Sirius in training and often provides a calmer perspective within the crew. 7 30 58
• Ulti and Page One — Crewmates whom Sirius mentors. Page One idolizes him as “Big Brother,” while Sirius encourages both siblings to grow stronger. 58
• Black — Artificial ship spirit and companion entrusted to Sirius by Dr. Tsukimi. Sirius accepts responsibility for guiding Black’s unrestricted learning and relies on him for ship control, engineering, and armor. 275 435 478
• Hiyori — Trusted crewmate whose ability to hear Poneglyphs and understand Uranus assists Sirius’s search for ancient weapons and navigation of major mysteries. 349 494
• Shanks — A powerful pirate acquaintance who warns Sirius about Imu and challenges him to prove his strength before the coming conflict. 418
• Golden Lion — Defeated and spared by Sirius; Golden Lion later seeks his help after abandoning his former obsession with world conquest. 340
• Imu — One of Sirius’s greatest enemies. Imu breaks Sirius’s sword, confronts his berserk Awakening without fear, and remains the reason Sirius’s crew avoids returning directly to the Blue Sea. 470 478

Story Role / Major Arcs

• Deserted Island and Kaido’s Recruitment — Sirius survives alone after transmigrating, obtains the Fenrir Fruit, and is recruited by Kaido following their encounter. 1 2 3
• Beasts Pirates Training — He trains under King, befriends Yamato, Jack, and Black Maria, acquires a greatsword, and develops his Fenrir powers. 7 30 34 47
• Departure and Founding of the Sirius Pirates — Sirius leaves the Beasts Pirates, forms his own crew, reaches a one-billion-Belly bounty, and sets sail for the North Blue. 141 142 143
• Six Powers Deal — He exchanges Heavenly Gold for direct instruction in the Six Powers, prioritizing strength over wealth. 166 167
• Zephyr Pursuit — Sirius unveils his Seimei Kikan-enhanced giant werewolf form, defeats multiple Vice Admirals, then retreats to protect his crew. 192 193 194 196
• CP0 and Zero Conflict — He battles the Strongest Shield Zero, whose Hydra poison and future sight are countered by Sirius’s Devour, Haki, Seimei Kikan, and speed. 287 288 290
• Birka and the Moon — With Black and Enel powering the Sirius, Sirius travels to the Moon, explores Birkan ruins, and obtains the Star Chart. 331 333 336
• Ancient Weapons and Emperor Battles — Sirius locates Pluto, defeats Charlotte Linlin, reunites with Kaido as an equal opponent, and learns of the threat posed by Imu. 349 378 404 418
• Awakening and Escape into Space — Sirius’s power Awakens during battle with Imu, briefly turning him into a berserk colossal wolf before Yamato restores his consciousness. He then leads the crew into space to avoid Imu and continue growing. 470 471 478
• Starry Sky Voyage — Sirius obtains interstellar navigation technology, makes the Sirius Pirates known among spacefarers, and confronts the forces of Smelting Star. 483 484
• Uranus Training — He spars with Uranus to test his strength and help the Ancient Weapon learn Haki. 494 500

Trivia

• Sirius keeps track of his time on the deserted island by carving the character “正” into a stone. 1
• Kaido calls Sirius a “little dog,” while Yamato initially calls his wolf form a “super cool big doggy.” 2 7
• Sirius deliberately avoids using Yamato’s sword, Enma, because he knows of its dangerous tendency to drain its wielder. 34
• He considers his sword his best partner besides Yamato. 478
• Sirius has no interest in ruling the world; he values freedom, exploration, and lively adventure over conquest. 340 478