Katasuke Tōno

Katasuke keeps a short crop of brown hair and wears glasses over his brown eyes, and in his daily duties he is dressed in a full white lab coat with no forehead protector. When he takes the field he switches to the standard Konoha uniform, though his armband is white and stamped with the crest of the Scientific Ninja Weapons Team rather than the usual red.

Cheerful, eccentric, and tirelessly inventive, Katasuke ranks among the sharpest scientific minds in the village, yet he stays humble enough to acknowledge his limits and welcome the help of others. He throws himself into his work with obvious joy, dreaming of a day when ninjutsu can be modernized so that anyone might use it to better everyday life, and he is a passionate gamer who lends special-edition titles to Boruto, whom he fondly calls Young Lord. A genjutsu planted by an agent of Kara warps all of this, leaving him selfish, arrogant, and shameless enough to exploit Boruto's ambitions in defiance of the Hokage. Once the control is broken he is wracked with guilt over how his research was twisted into weapons, so much so that he comes to regret inventing it at all, until Boruto reminds him that a tool is only as good or bad as the use it is put to.

Although a tokubetsu jonin, Katasuke's own ninja repertoire barely reaches past the most basic academy techniques; his real weapon is his intellect, which produced the Kote and countless other tools. After the Fourth Great Shinobi War he led an effort to fit survivors with advanced prosthetics, work that later aided patients such as Ao and the ninken Chamaru. Corrupted by Kara's genjutsu, he pushed his Kote into the Chunin Exams against the Hokage's ban, feeding the device to Boruto until the boy's sudden use of Lightning Release: Purple Electricity gave the scheme away and Naruto disqualified him. When Momoshiki attacked, Katasuke recklessly fired on the invader and instead restored his strength before being struck down, surviving only to be taken into custody. Interrogation under Ibiki and Ino's mind technique finally uncovered and severed Kara's hold on him, and a remorseful Katasuke returned to his post. He went on to build a tool modeled on Momoshiki's absorption power, escorting it toward Ryutan City with Team Konohamaru, where Ao stole one of the gauntlets before Koji Kashin killed the rogue shinobi. In the arcs that follow he studies the extraordinary body of Kawaki, helps repair the boy's arm, and works closely with the Kara defector Amado, growing more alarmed as the true danger of the Otsutsuki comes into focus.