WARNING: The following contains spoilers for Chapter 64 of Boruto: Naruto Next Generations, “Control,” by Masashi Kishimoto, Mikio Ikemoto, Mari Morimoto and Snir Aharon, now available in English from Viz Media.
One of the most shocking aspects in the Boruto manga has been how many secrets Code holds. It wasn't clear that he was such an elite killer after his introduction as a purely failed vessel Isshiki didn't want, but after being bequeathed with all the alien's power, Code's turning out to be quite a handful. Now, Chapter 64 reveals he has a deadly trump card against the Karma mark -- and it could be what helps him break Boruto and Kawaki.
Boruto's trying to stop Code from kidnapping Kawaki in the Konoha forest, using his Karma mark to tap into Momoshiki's power. But as he unleashes a bevy of overpowered moves from shadow clones to Rasengan bombs, Code is avoiding them, using his own teleportation bands to pop all over the place.
Boruto thinks he can use the Karma to absorb the black bands, as Code must be using a teleportation jutsu that relies on chakra. However, he can't absorb the bands because they've got a secret component: iron, which Code also has in his bloodstream, all due to the makeup of his robotic body given to him by Amado.
This means absorption is nullified because the bands are partly corporeal -- meaning physical objects that exist outside of what a shinobi creates won't go into the Karma. It's a crushing blow as Kawaki and Isshiki have been seen absorbing so many attacks, from flame to water to wind, increasing their own chakra level. Momoshiki and Kinshiki did the same in Naruto when they fought the Hokage, so Boruto is dismayed he can't do it and now needs something to level out the playing field.
It also means whatever other attacks Code still has up his sleeve will be infected by iron, thus they won't be absorbed either. This places Boruto at a handicap, because he's still not as skilled with his Karma mark and hasn't perfected the Ōtsutsuki's powers. It makes Code's moves unstoppable, leaving Boruto wondering how he can limit him to one spot. The enemy's as quick as Sasuke or Minato (Naruto's father), and with attacks that Boruto can't suck in, the young shinobi can tell he's a sitting duck.
Code loves having the upper hand and, seeing as he's already worked this loophole regarding chakra, he's savoring every moment. Using Momoshiki's power is damaging Boruto's body too, so it's just a matter of time before whatever else Code has in his arsenal results in something scary and drastic.
In that sense, Code may surpass Isshiki -- which is what Kawaki feared all along, especially as he knows Code wants Naruto's head on a pike. Now Kawaki can tell Code has the means to do so, with Boruto -- Konoha's strongest shinobi at present -- not enough for the job.
