Tosaka

Pale-green eyes and a light complexion mark this slim, rather tall man, whose silver hair falls to about chin length with short bangs shading his eyes. For clothing he layers a lengthy orange top over a beige bodysuit, adding a white sun hat along with gloves and sandals both in brown.

He first comes across as an oddball who is nonetheless warm, pouring real passion into his bird studies and thinking nothing of climbing a tree to put a nest of chicks back. Grasping a subject, in his view, calls for all five senses, so he will even taste the vilest material. That friendly mask conceals a man indifferent to life who savors the suffering of others. As with Orochimaru before his reform, nothing outranks research and scientific progress for Tosaka, and he chases it by whatever route works, owing loyalty to no one and readily manipulating or murdering those nearby to reach his ends. He judges his own mind and gadgetry to sit well beyond Orochimaru's, a swagger that curdles into rash overconfidence and premature victory calls.

No shinobi himself, Tosaka was pulled onto a ninja investigation because of his encyclopedic grasp of birds, and he doubled as a capable scientist in chemistry and biology, entrusted with leading cursed-seal research and inventive enough to engineer Scientific Ninja Tools that copy and boost cursed seals. Once reports reached Konoha of birds savaging a village, he joined forces with Team 7 and Team 15, though his habit of dissecting every scrap of avian evidence turned the stomachs of his teammates. They found villagers falling ill under cursed seals and an unconscious Jugo in their midst; over the following days Tosaka helped treat afflicted birds, inspected Jugo, and pored over blood samples while subtly guiding the inquiry.

His real allegiance came to light when Boruto and Suigetsu unmasked the Land of Rivers researchers behind the epidemic: Tosaka sedated the two, admitting he stood with those researchers and had engineered the entire crisis so as to draw Jugo into the open and turn his cursed seal into a weapon. He had already crafted such a weapon and grafted it onto his own body, gaining boosted strength and the option of a partial or total transformation, which he used to slay the researchers before pursuing the mutating Jugo to the lakeside. There his augmented shape stood no chance against Jugo's Sage Transformation, which crushed his hand, pummeled him, and drained his cursed seal outright. He kept narrating the clash until he blacked out, and once the birds recovered, Karin and Suigetsu dragged the still-griping schemer off with them.