"The Invisible Jutsu" (見えざる術, Miezaru Jutsu) is chapter 40 of the Boruto manga.
Shikamaru is frustrated the children left without even knowing how many enemies to expect fighting. He is informed that Sasuke has returned, but is seriously injured and unconscious, so they'll have to wait until they can follow. Boro notes their location is only accessible through space–time ninjutsu and asks Kawaki how he got there. Kawaki ignores him and asks about Naruto. Boro is intrigued by Kawaki's attachment to Naruto, and teasingly reveals Naruto is sealed in the container he's holding. When Boruto asks what they did to him, Boro throws them the container, telling them to check for themselves. As Boruto examines it, Boro explains only Jigen can undo the seal, and advises them not to force it open, as he can't guarantee the contents' safety. Kawaki senses Naruto's chakra inside with his prosthetic hand. When he turns to face Boro, he's disappeared, having used the container to distract them. Mitsuki detects his incoming attack from below, a surge of acid. Kawaki sees the acid engulfing Naruto's seal, and moves to absorb the acid with his Kāma. He's relieved when he checks it for damage and finds none. Boro uses Kawaki's distraction to douse him in acid, but Boruto steps in and absorbs it as well, confirming Delta's report on Boruto. Boruto calls out Boro on sneaking around, who challenges Boruto to come at him. As he does, Boro weaves hand seals. Boruto charges, against Sarada's warnings, stressing them don't have time to waste. Boruto lands a Rasengan, and Boro comments on its strength as he heals from the damage. Kawaki advances, wanting to overwhelm Boro's ability to regenerate with constant damage. Sarada notices Boro's hand seals again. Kawaki strikes, modifying his arm to toss Boro around. Boruto prepares to strike another Rasengan, but suddenly falls to the ground paralysed. Kawaki is also unable to move. He notices a dark mist from Boro's jutsu, but is unable to absorb it. Boro kicks Kawaki. Sarada wonders why they can't absorb the mist when they've been able to absorb all other jutsu. Boro addresses Boruto as Momoshiki's vessel, expressing gratitude for relaxing the time constraints on Kara's plans. Mitsuki attacks with Wind Release, trying to push Boro aside, but his dark mist remains in place. Mitsuki attacks with a lightning snake, which Boro blocks with a water wall. Mitsuki's actual snakes go around the wall, and wrap around Boro. Boro simply moves himself, using the snakes to pull Mitsuki and throw him down. As the snakes release him, one of them bites him, envenoming him. He weaves seals and heals. Mitsuki is concern by their long exposure to the mist, and Boro moves to end Mitsuki, as he's only interested in the vessels. Sarada throws a huge boulder at Boro, giving them an opportunity to take Boruto and Kawaki, and retreat. Boro notes he still has Naruto, and challenges Kawaki to return. Kawaki accuses Sarada of abandoning Naruto, but she denies it, saying they'd have been defeated. Sarada stresses they need to figure out Boro's jutsu first, and emphasises teamwork is their basic tenet as shinobi. They prepare to counterattack.