kaigaku

Though outwardly brash, haughty, and arrogant, Kaigaku is in fact cowardly and selfish. An orphan who grew up with nothing, he resorted to doing any immoral or demeaning acts as a means to survive, like thievery and drinking from a puddle. This attitude also was evident during his time as a Demon Slayer; unlike those who join the Demon Slayer Corps, Kaigaku never developed a desire to slay demons or protect people. When confronted with a stronger opponent, Kaigaku immediately surrenders, once again cementing his cowardice and indifference towards making immoral choices if it will save him in the end. However, despite his disinterest in becoming a Demon Slayer for the greater good, Kaigaku did show a desire for a status as a master swordsman. This is shown when even as a demon, he chooses to make his flesh weapon of choice resemble a Nichirin Sword. Kaigaku also possesses a twisted perspective of "right" and "wrong", believing that those who judge him right (i.e., say he is worthy) are good and those who judge him wrong and have a low estimation of him are evil.

When he became a demon, he is shown to be wearing his signature kimono secured with a blue obi over a stylized version of his Demon Slayer uniform that has yellow flame-like markings near the chest area and has it's collar unbuttoned. His forearms are seemingly wrapped in white kyahan-like material. He also wears multiple necklaces on his neck and wrist with light-turquoise colored strings that hold together blue magatama-like pendants that were yellow in color when he was human.

As a human, Kaigaku is a muscular young man of average height and pale skin tone who has short, spiky black hair, with two thick strands framing his face, and a pair of dull, cold teal eyes framed by thick, arched eyebrows. His facial expressions are often unfriendly, and he has a semi-permanent snarl.

After becoming a demon, he gains many demonic traits, including four navy blue flame-like markings on both sides of his cheeks, emerald green irises (originally colored cyan in the manga) with black sclera, elongated canines resembling fangs, sickly pale skin, sharp blackened nails, and pointed ears. By becoming a member of the Twelve Kizuki and rising to the position of Upper Rank Six, his eyes are etched with the kanji of "Upper Rank" on his right, and daiji of "Six" on his left. When he was still human, who is still undergoing training under Jigoro Kuwajima, he is shown to be wearing a black kimono with a white collar, worn loosely to expose his chest and his signature magatama-necklaces around his neck, with the magatama being in gold and the string in blue. When he became a Demon Slayer, Kaigaku wore the Corps’ standard uniform consisting of a navy gakuran-style button-up jacket, with a stand-up collar and long sleeves, featuring silver buttons and a shirt pocket on the left breast, with the kanji for Destroy engraved on the back of the uniform. Beneath the jacket, he wore a white long-sleeved collared undershirt. His uniform also included a pair of matching navy tattsuke-hakama held up by a white belt, tucked into white kyahan wrapped around his ankles. On his feet, he wore navy tabi socks and a pair of zori sandals with blue straps.