WARNING: The following article contains spoilers for the Boruto: Naruto Next Generations anime, Episode 101: "Jugo's Reinforcements."
With the Cursed Seal infection around Konoha in the Boruto anime's latest arc, fans immediately believed the virus was being spread by none other than Orochimaru. After all, in the Naruto franchise, the snake-ninja experimented with this taboo mark and created weapons of mass destruction like Jugo and Sasuke.
But although that speculation would have held water earlier, as the series -- especially the manga -- progressed, we saw Orochimaru embarking on his own path of redemption. Now he's officially no longer a suspect, because the latest episode unveils a new Orochimaru on the block, and it's someone who's shaping up to be just as sinister, if not worse.
When Jugo's Cursed Seal began transforming him into a rampaging Hulk once more, it was difficult not to point fingers at Orochimaru. But since he helped Naruto's army in the last ninja war against Kaguya, the mad scientist (along the lines of X-Men's Mister Sinister) has been operating on missions of progress, trying instead to help the shinobi world. Of course, he can't be fully trusted, so Konoha dispatched agents to monitor his activities. For Orochimaru to have been the villain, he'd have needed to elude Naruto's most trusted spies.
Still, the Cursed Seal isn't something just anyone can manipulate, and Orichimaru was the only genius at doing so. Or so we thought. His apprentice Kabuto did exploit it briefly, but he too is performing social work with orphans, and redeemed himself after Naruto ended. So with the prime suspects out of play, theorists went back to the drawing board, considering whether a new science overlord emerged under the radar. Shockingly, it turns out to be Tosaka, a kindhearted medical expert who helps bordering villages.
When Boruto's team meets Team Taka in this episode, they conclude the best decision is to take Jugo back to Orochimaru for healing, as the snake-ninja knows his physiology best. But Jugo has been taken by a mysterious research team that wants to experiment on him to find a cure. That sets Boruto and Suigetsu off on a hunt. Sadly, however, they run afoul of rogue kids who have been turned into assassins by Cursed Mark collars.
Eventually, they find Jugo at a lab, but in a stunning move, Tosaka sneaks up, and injects and neutralizes them. We discover he isn't actually trying to discover a cure; he wants to spread the infection. He had to take evasive action when the heroes figure out this lab is filled with sadistic experiments, and is where he preys on kids like the Orochimaru of old. He had everyone fooled into thinking he was a genuine doctor. Instead, he's merely obsessed with bringing death and destruction to the ninja alliance.
With so many villages at risk, and Tosaka's ruse leaving everyone none the wiser, the future looks bleak. We don't know what inspired his motivations or the depths of his experiments, but clearly Tosaka has a grudge he wants to settle. And if he successfully infects Boruto and Suigetsu, as the final scenes hint, along with Jugo, Tosaka may finally have started assembling an army he can control with the Cursed Seals, which would spell doom for Naruto and his allies.