Kidnapped! Naruto's Hot Spring Adventure!

is episode 97 of the original Naruto anime.

Synopsis
On their way back to Konoha, the group takes a break at a hot spring town. Naruto Uzumaki learns that Senta and Bunzō (two ninja of the Akagi family) cannot return home unless they collect Tsunade's debts, and attempts to help them. Shizune, fearing that Tsunade's debts, if exposed, would jeopardize her chances of becoming Hokage, disguises herself as Tsunade to stop Naruto, but neither of them realizes that the debt had already been paid.