"The Fifth Hokage! A Life on the Line!" (五代目火影 命を賭けた戦い, Godaime Hokage, Inochi o Kaketa Tatakai!) is episode 95 of the original Naruto anime.
Despite trying to heal himself after being hit with the Rasengan, Kabuto's wounds are too extensive for him to deal with and he collapses. However, he manages to have torn the muscles surrounding Naruto's heart, causing Naruto to begin dying. Tsunade does what she can, determined to save him. Her efforts work, and Naruto regains consciousness long enough to claim the necklace he has won. After he falls asleep, Tsunade puts the necklace around his neck, hoping that he will some day become Hokage. Orochimaru, recognising Naruto as a potential future threat, tries to kill him. Tsunade, determined to make sure Naruto becomes Hokage, overcomes her fear of blood and uses herself as a human shield to block the attack. When asked why she would risk her life to save him, Tsunade replies that it is her duty as the Fifth Hokage, finally accepting the role she was offered. She then unleashes the seal on her forehead and uses a regenerative technique that heals her of her injuries. Intending to eliminate Orochimaru once and for all, Tsunade prepares to summon Katsuyu. Jiraiya and Kabuto both recognise the technique she is about to use, and the two quickly summon Gamabunta and Manda.