WARNING: The following article contains major spoilers for Boruto: Naruto Next Generations #39 by Masashi Kishimoto, Mikio Ikemoto and Ukyo Kodachi, on sale now.
In the Boruto manga, the terrorist cell Kara has been revealed as the dark shadow looming over the free shinobi world. Recently, we discovered its leader, Jigen, is actually a vessel for Isshiki Ōtsutsuki, an alien affiliated with Naruto's past nemesis, Kaguya. This indicates his legion on Earth is way more sinister than first imagined and could be executing Kaguya's plan to enslave humanity once more, with Jigen more or less being her successor.
However, Boruto #39 has confirmed that despite thinking Jigen's the tyrant we should be fearing, there's actually another killer in Kara worse than him: Boro.
When it comes to Kara, the series has smartly kept a shroud of secrecy over who else within Jigen's inner circle can act as a weapon of mass destruction. We've seen the mysterious Koji Kashin investigating and scouting for Jigen rather than causing wars, Delta already engaged Naruto in battle and got a sound whipping, and Amado's been seen as Jigen's chief scientist. But when Boro appeared before, it was in cameos, and he never showed his hand too much.
In the Ao arc where Boruto befriended a young kid being bullied, we saw Boro in a meeting held by Jigen about the urgent matter of the missing Kawaki, before the kid ended up in Konoha under Naruto's wing. Boro was adamant they recover the vessel at all costs, but at that point, nothing was known about any of the new villains, including their power-sets or intentions. Nonetheless, they were intimidating.
Kawaki gave Boro a bit more agency later on, though, and after Naruto roughed up Delta, we saw Boro's arrogant side as he made fun of the disheartened warrior. She failed in her attempt at retrieving Kawaki and Boro took pleasure in her frustration. No one ever spoke out against him, however, hinting he was way senior or they were afraid of him as a general.
Even Jigen seemed to have a bit more respect for Boro than the others, which came to light when Boro was informed Koji was observing Kawaki in Konoha instead of taking action. Boro grew suspicious and dropped hints he was going to get more hands-on in getting Kawaki back and stopping Naruto's village from scuppering their own plans.
The end of the latest chapter reveals the big twist that Boro's actually guarding Naruto in the chamber Jigen sealed him away in. We see him there, waiting in case anyone comes to rescue Naruto. Given this huge responsibility has been placed on his shoulders, we know Boro shouldn't be messed with. Kawaki makes it clear he's worse than Jigen and that he can actually traverse the space-time dimension, which means Boro can even rival Sasuke.
The usually cool Kawaki's scared in this secret dimension as everyone finds out the ultimate assassin is overseeing Naruto. Sadly, Kawaki doesn't think he, Boruto, Mitsuki or Sarada are equipped to handle this situation because they're facing the deadliest of the Kara bunch.
Jigen has said in the past Boro does have monstrous power, and seeing as Kawaki was so familiar with Kara before he ran away, if he says this man's deadlier than Jigen, you best believe it. He knows Boro well and the fact that he inflicts a fear in the boy not even Jigen could means we should expect the worst, because Boro has already indicated he has no problem killing kids to maintain Kara's vision of a better world.
Boruto #40 goes on sale Nov. 20.