Killer B

- Killer B's appearance as a child - Killer B's full appearance. - B's appearance in the New Era. 1/3 Killer B has dark skin and a muscular build, as well as white hair (blond in the anime) and a goatee. On his right shoulder, he has a tattoo of the kanji for "iron" (鉄, tetsu), which is the Iron Armour Seal that was used to seal Gyūki into him, and on his left cheek, he has a tattoo of a bull's horn (correspondingly, Gyūki has horns like a bull, and the left one is partially missing). His top lip also has a slightly darker hue than his bottom one. Killer B wears oval-shaped sunglasses and a white-coloured forehead protector. He also has his village's standard one-strap-over-one-shoulder flak jacket, and a long, red rope belt tied around his waist, the standard Kumo hand and shin guards, shinobi sandals, and a white scarf around his neck. In the anime the trim on his flak jacket is white, but in the manga it is yellowish. He originally carried seven swords on his back, but now he only carries two swords on his back and stores the rest inside Samehada. As a child, B's hair was much shaggier and he wore a simple suit along with his trademark sunglasses and scarf along with Kumo-nin shin-guards. In his adolescent years, his hair grew much longer and he wore it in a stylised, combed-back manner. In these years he donned the standard uniform of the Kumo-nin inclusive of shirt and started carrying two particular swords. As he got older, he started wearing his forehead protector like a bandanna. Years after the Fourth Shinobi World War, B's attire consisted of a long, dark, sleeveless vest that left his abdomen exposed along with baggy white pants held up by a cord and standard shinobi sandals. His hair had also gotten noticeably longer, his goatee became shaggier and covered his lower jaw, plus his brow becomes hairless and more prominent.

At a young age, he was along with several other children who were gathered by the Third Raikage and Dodai in order to select a tag partner for his son A. Out of all the children gathered, he was the only person able to successfully perform the Lightning Release: Double Lariat with A. As such he was given the name "B", and A stated they would be brothers from that day on. Since the age of five, B has been best friends with Motoi, whom he always greeted with a fist bump. After A's cousin, the jinchūriki of Gyūki lost control and killed Motoi's father along with seven other ninja on that day, B was chosen as its next jinchūriki. Soon afterwards, B suffered from similar prejudices against jinchūriki, not too different from that the villagers of Konohagakure and Sunagakure had against Naruto Uzumaki and Gaara respectively. However, he kept smiling and pushed himself to be the best jinchūriki that he could be, so that his brother wouldn't be hurt politically as the Fourth Raikage. After his father's death, Motoi tried to kill B, believing that B's death would also kill Gyūki and avenge his late father, but B disarmed him easily and held no ill will against Motoi. Motoi however, was ashamed of his actions and did not speak to B for over thirty years because of it. B would later train with his brother on an island in the Land of Lightning, where there he would find the Falls of Truth. There he learned how to control Gyūki in an amazingly short period of time. Some time after his training, B, alongside A, and other Kumo shinobi confronted Minato Namikaze and his small squad. When Minato moved to counter A's attack, B used a tentacle to push A out of the way, causing shock to the Konoha shinobi that he was Gyūki's jinchūriki. The two from this encounter Minato would come to have much respect for B and his abilities. Minato even stated that B acted as a true shinobi killer, thus giving him the title of "Killer". Some time since then, much like Naruto, B has become beloved in Kumo as the village's hero, or, as Motoi called him, the "Hero of Heroes". When A became the Raikage, he forbade B from fully transforming into the Eight-Tails and restricted him from leaving the village, saying instead that he would become the guardian of the village and attack from within its walls, to protect him from meeting the same fate as his adoptive father. Sometime later, when B learned from pestering Darui that Konoha and Suna were hosting together an impromptu Chūnin Exams, B saw this as an opportunity to give a show for the attendees. A however anticipated his young brother's actions and had Darui and C stop him.