The Shinobi Prison: Hozuki Castle

A boatload of convicts arrives at Hozuki Castle, where each is branded on landing, and hidden among them are Boruto and Mitsuki. The warden Mujo outlines their new circumstances before passing the briefing to Benga, and a prisoner's failed escape attempt triggers Mujo's restraining technique. In flashback, the pair recall their assignment: slip inside and pry from a former Mujina member the identity of the bandits' leader before the gang can silence him.

Because arranging outside protection for the informant Kokuri would have taken too long, and because Kusagakure, which oversees the prison, feels little urgency over crimes that never touched it, Konoha instead struck a deal with the castle's master to stamp Boruto and Mitsuki with counterfeit brands. Sarada rounds out the operation by posing as a student journalist researching the facility. Introduced to their cellmates, the two boys spin a cover story as Land of Water robbers serving eight-year terms.

An inmate named Arai points the newcomers toward the prison's smuggling contacts and lays out the situation: the Mujina's second-in-command, Tsukiyo, sits in solitary after brawling with Kokuri, who has since been moved to the medical ward. Reaching that ward is difficult, but Arai notes that swallowing the poisonous plants growing around the grounds should do the trick. Mitsuki secures a specimen with the help of a snake, and Boruto eats the toxic fruit to get himself admitted.

Waking a day later, Boruto is knocked out and then restrained by a terrified Kokuri, who assumes the boy has come to kill him, until Boruto explains that Konoha received his letter and sent them in response. From his cell, Tsukiyo passes messages by note, and as Boruto is escorted back toward the general population, an intruder slips into the ward where Kokuri is held and knifes him at Tsukiyo's behest.

Episode 141 opens the Mujina Bandits Arc, airing in Japan on 26 January 2020 and in English on 23 November 2021, with the opening Teenage Dream and the ending Fireworks.

The installment tidies up a long-standing wrinkle around Hozuki Castle. The film Blood Prison placed it inside landlocked Kusagakure despite showing it beside the sea, so this episode instead describes the castle as merely administered by Kusagakure. It also sets aside the novel Kakashi Hiden, which had installed a new warden wielding Ice Release, by stating that every warden descends from the same clan bound to a Fire Release restriction technique.