Inheritance! The Necklace of Death!

Inheritance! The Necklace of Death is Naruto episode 91

This episode starts when Naruto try to hit Tsunade with his not perfect yet rasengan. But Tsunade dodges it easily, then she berated Jiraiya for teaching Naruto a technique he couldn't possibly master. Naruto insisted that he could, and bet that he could learn it in three days. Naruto's personality reminded Tsunade of her deceased loved ones, so she took the bet, giving Naruto a week. If Naruto won, she'll accept that he can become Hokage, and give him her incredibly valuable necklace that originally belonged to the First Hokage. Naruto accepted it

Later, Shizune talk to Naruto about Tsunade's past and the history of the necklace. Shizune said that the necklace isn't a ordinary necklace .If anyone except Tsunade wears it, the people will die. While Shizune talks to Naruto, Tsunade is on the gate of Tanzakugai, thinking of her past.