Akaza was a well-built young man of average height with pale skin that had a faint greenish tint. His body was marked with thick blue lines resembling the criminal tattoos he had as a human. He had short, bright pink hair that flared out around his head, and yellow eyes with pink eyelashes and blue, cracked-glass-like sclera. The kanji for “Upper Rank” (上弦) was etched into his right iris, and the daiji for “Three” (参) into his left.

Blue lines curved from below his ears across his temples, with another running from his hairline to the bridge of his nose. Two lines wrapped around his neck, and three extended from the lower one onto his torso: the center line ran down his chest to his stomach, while the side lines curved over his chest. A similar pattern circled his waist. On his arms, lines ran from his shoulders, looped around his biceps, and continued down to his wrists. Each finger was dark blue with orange nails. His toes and toenails matched.

He wore a short, sleeveless dark purple-pink haori, open at the front and cut off at the waist, with a square pattern on the back. His pants were loose and white, rolled just below the knees, held up by a turquoise rope belt with bright pink tassels at the front and back. Akaza went barefoot, wearing only chains of large pink pearls around his ankles.

Akaza tries to coax Kyojuro into becoming a demon

Akaza was a headstrong, stubborn, and battle-obsessed social Darwinist who relished combat, especially against powerful Demon Slayers. He often prolonged fights intentionally, savoring every moment not out of cruelty or masochism, but from a deep admiration for his opponents’ strength and skill. Whenever struck by a powerful attack, Akaza would become visibly enthralled, frequently offering praise for his adversaries’ techniques and swordsmanship, calling them magnificent and fascinating. He held a deep disdain for those he considered weak, so intense that even their presence made his skin crawl. Conversely, Akaza showed genuine respect for the strong. He demanded to know the names of those he deemed worthy and would not rest until he did. As a tribute to their strength, he remembered each name, honoring them by committing them to memory.

Akaza often extended an offer to those he deemed strong, urging them to become demons. He believed that preserving their refined techniques and exceptional skill was the right thing to do, feeling genuine sorrow at the thought of such talents fading with age. To him, allowing gifted warriors to deteriorate was a waste, and if they refused his offer, he would sometimes kill them himself—believing it a way to preserve the brilliance of their abilities. Akaza held no prejudice against those who were once weak, as demonstrated when he praised and acknowledged Tanjiro Kamado’s growth, despite having initially tried to kill him for his lack of strength. He even thanked Kyojuro Rengoku for helping Tanjiro reach that level. Akaza’s worldview was rooted in a strong belief in social Darwinism; he saw strength as the ultimate virtue and believed the natural order demanded the elimination of the weak.

Akaza possessed a deeply rooted psychological drive to become stronger. Although he generally respected powerful individuals, he had a combative relationship with his fellow Upper Ranks, viewing them more as rivals than allies. This was especially true for the two ranks above him—Doma and Kokushibo—toward whom he showed open hostility. He frequently lashed out at Doma and even vowed to kill Kokushibo out of jealousy and resentment.

Akaza’s obsession with strength ran so deep that even after being beheaded in his battle against Tanjiro and Giyu Tomioka, he refused to die. Driven by sheer willpower and unrelenting resolve, he continued fighting, declaring that he must become the strongest no matter what. In doing so, he temporarily overcame the fundamental demon weakness to decapitation by a Nichirin Sword—a feat achieved through will alone.

It was later revealed that Akaza’s relentless pursuit of strength was rooted not in pride, but in tragedy. As a human, his desire to become stronger stemmed from a desperate wish to heal his sick father and protect the people he cherished, especially his fiancée Koyuki and his mentor Keizo.

Akasa’s Blood Demon Art

As the third highest-ranking member of the Twelve Kizuki, Akaza was an exceptionally powerful demon and considered the fourth strongest overall, behind only Doma, Kokushibo, and Muzan Kibutsuji. Even as a child, before receiving any martial arts training, Akaza was capable of defeating and knocking out grown men on his own. At the age of eighteen, after mastering the Soryu Style under his teacher Keizo, he singlehandedly defeated sixty-seven trained adult swordsmen using only his bare fists. His ferocity and skill were so overwhelming that Muzan initially believed a demon had been responsible for the carnage.

Upon becoming a demon, Akaza’s combat abilities increased dramatically. Despite limiting his own growth by refusing to consume women, he still rose to the position of Upper Rank Three among the Twelve Kizuki. He was strong enough to battle the Flame Hashira, Kyojuro Rengoku, on equal footing and ultimately killed him. Over time, Akaza claimed the lives of numerous other Hashira and Demon Slayers, becoming one of the most feared demons in existence.

Akaza showcased the full extent of his power during his battle against the Water Hashira, Giyu Tomioka, and the Hashira-level Demon Slayer, Tanjiro Kamado. Even when facing two powerful opponents at once—both of whom had activated their Demon Slayer Marks—Akaza dominated much of the fight. He was only pushed back when Tanjiro briefly accessed the Selfless State and Transparent World. Despite being decapitated, Akaza continued to fight, with his headless body nearly regenerating completely. The battle could have ended in the deaths of both Demon Slayers had Akaza not chosen to stop fighting on his own.

Although Akaza was ultimately unable to defeat Kokushibo when he challenged him for the position of Upper Rank One, Kokushibo spared his life. This was a rare event, as Kokushibo had previously killed every other demon who attempted the same. His decision to let Akaza live suggests that, despite the gap in strength, Akaza put up a formidable fight that Kokushibo found entertaining.