The Mobile Fortress

Buntan reads their find as proof of the rumors she had heard about the Funato, and Boruto insists on alerting Kagura. After Iwabee confirms no ships are chasing the freed hostages, Sarada radios in their rescue, and Kagura reveals the existence of a mobile fortress he dispatched Boruto to investigate. The two sides trade updates: the fortress is advancing on the rendezvous, and if it spots Sarada's ship, its scientific ninja tool will destroy it outright. When a Funato vessel rams Kagura's boat, Boruto resolves to take out the weapon himself, and Kagura offers up Taiki's crippled boat as a decoy.

Taiki's boat slams into the fortress, pulling the Funato away long enough for Boruto's group to close in. Two guards catch them, and Buntan drops one with a Lightning Ball before the other flees for reinforcements. Kawaki proposes wrecking the door to buy time, and Kagura arrives with Hebiichigo and Kyoho after beating the last guard, Hebiichigo stitching the door shut behind them. Tenma Funato then appears, dismayed to find only children, and summons a fiddler-crab pincer to counter Hebiichigo's attack. The sight of her blood sends Kyoho into a frenzy, and his Kabutowari strikes rattle the fortress enough to reveal a route atop the weapon, though his rage also turns on Boruto and Kawaki until Kagura knocks him out and takes over the duel.

Boruto reaches the chakra cannon just as it locks onto the ship and starts charging. Iwabee spots the threat in time for Denki to swerve clear of the first shot. As Buntan holds off the guards, Boruto uses a maintenance crane to wrench the cannon around while it fires, tearing into the fortress, and Kawaki and Kagura pin Tenma so he cannot stop the shot. With the structure collapsing, the group escapes as Tenma swears revenge. Everyone reunites at the ship, the swordsmen celebrating the reduced sentences their success has earned, and Kagura orders a course back to Kirigakure to get the group home safely.

Taiki's boat is sacrificed as a distraction to let Boruto's team board the fortress. Kyoho's rage destabilizes the structure and exposes a path to the weapon. Boruto swings the chakra cannon with a crane to wreck the fortress from the inside, and Kagura's crew holds Tenma back long enough for the strike to land before everyone escapes and regroups.

The episode is part of the Great Sea Battle of Kirigakure storyline, an anime-original arc in Boruto: Naruto Next Generations. It runs under the opening theme GOLD and the ending theme VOLTAGE.