"Rogue Ninja's Past" (抜け忍の過去, Nukenin no Kako) is episode 147 of the Naruto: Shippūden anime.
Naruto, Sai and Yamato attempt to attack the Kirihunter-nin, who use their Secret Technique: Mist Rain to absorb the chakra from Naruto's Rasengan while using Water Release: Water Whip to destroy Sai's ink beasts. Their clash is interrupted by Tsurugi, the commander of the hunter-nin's unit. Since Team 7 refuses to hand over Utakata in exchange for Hotaru, Tsurugi offers a counter-proposal — Utakata would be allowed to stay with Hotaru until Team 7's mission is done, at which point Team 7 is relinquish Utakata to Kirigakure; failure to comply could incite a war between the nations. As Yamato agrees, Tsurugi asks for a private conversation with Utakata. He asks Utakata to return to Kirigakure, claiming that they are not known as the "Blood Mist Village" anymore and that things are peaceful there, and that the village won't kill him since he possesses something they need within him. Utakata refutes Tsurugi's words, not wishing to trust him, stating that the last time he trusted someone, who happened to be his master, the latter turned around and tried to kill him.
With Yamato and Tsurugi having agreed to a negotiation, the hunter-nin flee. On their way back to Mount Katsuragi in order to reunite with Sakura and Tonbee, Hotaru wonders why Utakata does not wish to be her master. Naruto tells her about his master, adding that since he did not have any parents growing up, travelling with Jiraiya made him wonder if that is what it felt like to have a father, and that he even found himself acting like a son. He recalls how hard he trained under his master, and reassures Hotaru that so long as she possessed the will, she will be his student. However, Hotaru collapses from pain, and Naruto notices that her shoulder is hurt. Utakata realises that it is her back, and asks for some privacy while tasking Naruto with finding some medicinal herbs. As Naruto retrieves the herbs and makes his way back, he is stunned when he sees Hotaru's bare back, with contains a scarred seal. Utakata reveals that the scar is the Tsuchigumo clan's forbidden technique, which was engraved on to her. Filled with rage, Utakata declares that he has no care for those who merely use people as tools or vessels with no regard for their welfare.