"Sakura's Determination!" (サクラの決意, Sakura no Ketsui) is episode 141 of the original Naruto anime.
Naruto takes on Arashi, but gets trapped easily. Sakura thinks he's dead and Naruto ends up blowing his sneak attack cover to protect her. Naruto tries his attack again, but his injury causes a problem. Naruto gets trapped in an attack that will crush him if he doesn't get out. Sasame attacks Arashi and manages to set him free for a second. However, it doesn't last long and he soon tries to kill Sasame. Sakura jumps in the way and says she will give her life to protect her friends. Naruto tells her she can't die and Arashi tries to finish Naruto off. Sasame causes a distraction enough for Naruto to break free. The resulting explosion of Naruto's escape from the trap creates shrapnel, which strikes Arashi, freeing him. Arashi protects Sasame from harm, but the lair begins to collapse just as Jiraiya and Gamahiro arrive. Arashi throws Sasame to Jiraiya and tells them he can't leave since he is a puppet. He tells Naruto that Sasuke is alive and being protected as a vessel until Orochimaru can reincarnate again in three years. After hearing this the group leaves, leaving Arashi behind. The Fūma clan promises to rebuild their town and everyone heads back to Konoha. Back in Konoha, Shikamaru remarks to Tsunade that a medical-nin should be part of all small platoons. Tsunade acknowledges that she wrote the same thing once, but training to become a medical ninja requires special qualities that few possess. Considering herself to have been of little use, Sakura asks to become Tsunade's apprentice and learn to become a medical-nin, to which Tsunade agrees.