Kokushibo

Flesh Sword - Kokushibo reveals that he separated part of his flesh and shaped it into the katana he now wields. The sword is dotted with eyes on the blade, hilt, and guard, increasing his range of vision in combat. Furthermore, since the sword is crafted from Kokushibo's flesh, it easily regenerates damage. This ability was demonstrated when the blade returned to its original form during his fight with Gyomei Gimejima. Kokushibo later freely altered the sword's form, growing three additional blades to increase its reach. He can also regrow blades from his body.

Kokushibo uses the Breath of the Moon, one of the most dangerous in the world. Shinazugawa Sanemi noted that when Kokushibo swings his sword using this style, he surrounds the opponent with chaotic, crescent-shaped movements that constantly change size and length, thereby increasing the range of damage. +First Style: Dark Moon: Evening Shrine - Kokushibo makes a quick attack with his katana, and several crescent moons appear in the trajectory of the cut. +Second Style: Moon Pearl Flowers - Kokushibo creates ascending vertical slices around himself. +Third Style: Hateful Moon: Chains - Kokushibo makes many chaotic cuts in front of him. +Fifth Style: Ghost Moon Destruction Whirlwind - Kokushibo creates multiple curved slices, layered on top of each other, resembling an ascending whirlwind. Numerous chaotic blades emanate from these slices. Kokushibo performed this attack without swinging his sword. +Seventh Style: Lonely Moon in the Endless Night of Avichi - Kokushibo creates several ground-ripping slashes in front of himself. +Eighth Style: Moon Ouroboros - Kokushibo performs a large-range circular attack. +Fourteenth Style: Disaster - Immortal Proud Crescent - a multitude of horizontal slashes surrounding Kokushibo in such a way that it cannot be approached

Kokushibo was an extremely powerful swordsman, considered the strongest of the Twelve Moons Demons and the second strongest Demon in the series, after Muzan Kibutsuji. As one of the oldest demons in the series, he had fought numerous demon hunters and gained vast experience and knowledge in combat. He was able to easily decipher the techniques and skills of at least two Hashira and crush them in combat. +Increased speed: +Durability +Strength and reflexes +Transparent World (透すき通とおる世せ界かい Sukitōru Sekai): Kokushibo gained the ability to see the "transparent world" through the use of three pairs of eyes. This gives him superhuman kinetic vision similar to Kanao Tsuyuri, allowing him to see the muscles, blood flow, and joint movements of his opponents. He can accurately predict and anticipate his opponents' movements and attacks with this ability. +Improved regeneration +Demonic transformation

It is unknown when exactly he became a demon and joined the Twelve Demon Moons, but the impetus for this decision was the realization that people with the mark do not live past the age of 25. 60 years later, on the night of the blood moon, he met his brother Yoriichi Tsugikuni, who almost cut off his head, but died of old age at the last moment.

Three hundred years ago, Kokushibo met a demon hunter who ate demon flesh to increase his powers. Kokushibo defeated him by cutting him in two.

Before meeting Muzan, Kokushibo was a human and one of the strongest demon hunters. He lived during the Sengoku period and perfected his sword skills with a former wind breathing user. It is also known that Kokushibo was familiar with the Wind Pillar. He later had a child who continued his lineage.

Kokushibo's real name before meeting Muzan was Michikatsu Tsugikuni.

He was born along with his younger brother, Yoriichi, during the Sengoku period. His family was of high class. Their father decided to make Michikatsu his heir when he turned 10 and send Yoriichi to the temple. Michikatsu pitied his younger brother, but was not allowed to approach him. Nevertheless, he approached him and presented him with a homemade flute. This earned him a punch in the face. When they were both seven, Yoriichi asked Michikatsu to try his hand at fencing. Michikatsu was amazed by Yoriichi's skill. Yoriichi defeated his teacher in just a few moves. From then on, Michikatsu despised and envied Yoriichi's talent. When he learned that Yoriichi had always been picking on his mother's weak spot, his hatred grew.

Having learned of Yoriichi's talents, his father decided to make him his heir. Yoriichi ran away from home after his mother's death. Ultimately, he was never found, and Michikatsu became the heir.

Little is known about Kokushibo, as he is very secretive.

Judging by his behavior at the Upper Moon meeting, one might assume he is punctual and takes his job very seriously. Kokushibo displays a strong sense of loyalty to Muzan Kibutsuji, and most of the actions of the First Upper Moon are dictated by a desire to be more useful in achieving his leader's goals. Kokushibo is a man of few words, and although he chooses his words carefully, they sometimes come across harshly due to their terrifying directness. This makes his threats especially frightening.

Later, we see a more human side of Kokushibo's personality: in memories of his family and brother, he is emotional, not a stranger to experiences, and in a fight with Muichiro, Tokito recognizes him as his descendant and positively evaluates his skill, ultimately offering to become a demon.

As a demon, Kokushibo is a pale-skinned, tall, and muscular man with long, spiky black hair with red tips, pulled back into a ponytail. His most notable feature is the three pairs of eyes on his face, each with yellow irises and red sclerae, each with a black, straight line running from each iris. His middle set of eyes contains the kanji for "Highest Rank (上じょう弦げん, Jōgen?)" and "One (壱いち, Ichi?)". Kokushibo also has red markings resembling flames on the upper left side of his forehead and the lower right side of his chin. Kokushibo wears a purple and black nagagi kimono in the shape of a beehive and a black umanori-style hakama with a white uwa-obi. He wears a flesh sword on his belt with eyes in the space between the tsuka tsuka ito. The tsuba and blade are later revealed to have eyes and veins. As a human, Kokushibo's appearance was nearly identical to his demon form, with the exception of the number of eyes, prominent eyebrows, and noticeably less pale skin. His eyes had dark purple irises and normal white sclerae, like man. As a child, he wears a white kimono, not the purple and black patterned one he wore as an adult.