Naruto is busy training, yet Tsunade calls for him. Once he arrived at the Hokage’s headquarter he asks what does she want. He also explains to her that he doesn’t have too much time since he wants to get back training new ninjutsu.
Tsunade is very proud of his hard work and offers him a “reward”. The first thing in Naruto’s mind would be a coupon for Ichiraku ramen, but that’s not what the hot female Hokage wants to offer him. Instead she offers to take his virginity, since A.) every dangerous missions could be his last one and B.) Sakura might be disappointed that he is still a virgin. So Naruto agrees and they both get naked. You can clearly see that Naruto still needs to learn a lot about a woman’s body. That’s why Tsunade teaches him about every little dirty detail he needs to know to become a sex god.
However, what she clearly underestimated was his sheer endless stamina. He fucks the hot Hokage MILF over and over again, and with every time she has a stronger orgasm.