Kawaki

Kawaki is a young man with grey eyes and bushy black hair, the sides of which are shaven and blond in colour. Additionally, he has a tattoo of the Roman numeral Ⅸ under his left eye, a pair of piercings on his right eyebrow, and stud earrings. Kawaki wears a green shirt with a blue sleeveless vest jacket with grey stripe patterns on the collar and dark pants with a studded belt. He has a Kāma on the palm of his left hand in the shape of a diamond, which spreads across the left half of his face, chest, and arm, glowing red upon activation.

Kawaki is shown to be highly aggressive and vulgar to people he dislikes or opposes. At the same time, he can remain calm and collected when questioning strangers. When not letting his temper get the best of him, Kawaki is shown to be very observant and problematic, easily reading the flow of battle before him and how best to react.

Kawaki (カワキ, Kawaki) is a child raised by Kara to be the future vessel for Isshiki Ōtsutsuki and the key to the fulfilment of their greatest wish. After being brought to Konohagakure by Team 7, he is taken in by Naruto Uzumaki who raises him as his own, during which he develops a brotherly bond with Boruto Uzumaki to solve the mystery of Kāma.

During his childhood, Kawaki was raised by his physically and emotionally abusive drunkard father, until Jigen bought him with a large sum of money. Upon taking custody of the boy, Jigen told Kawaki that the suffering he endured was over and there was nothing to fear, as he was his new father. Some time afterwards, Jigen took him to a laboratory where he met Amado, telling him that he would give him a gift when they truly become parent and child. Kawaki was one of fifteen children placed in artificial wombs connected by tubes to jars of fluid, through which Jigen attempted to transfer his Kāma to them. The first thirteen children all died, however Jigen succeeded with Kawaki, one of his last attempts. Kawaki later awoke with a Kāma branded on his left hand. Despite Jigen's promise of safety, Kawaki would later describe his life from then on to be a living hell. He would constantly be put through gruelling training, all so he'd master the Kāma and become a perfect vessel for Isshiki Ōtsutsuki, as Jigen wanted. During it, he would constantly berate Kawaki as only having value as a vessel for the Kāma and would strike the boy whenever he questioned him.

(Source: Narutopedia)