An A-Rank Mission: The Contest

is episode 309 of the Naruto: Shippūden anime.

Summary
Naruto arrives to help a team of Allied Shinobi Forces led by Karui, who are struggling against a reincarnated samurai, whom Naruto recognises as a man named Tatewaki he met on a previous mission. Naruto has a flashback to when Tsunade assigned Team 10 and Naruto to go to the Land of This and kidnap Shū, the son of the daimyō under a treaty. Shikamaru formulates a plan to capture the Shū by having Chōji enter an eating contest at the Land of This' castle and get second place. Chōji speeds through the competition, and before the final round, Ino uses her Mind Body Switch Technique to take control of Shū and goes to the washroom in the castle, where Naruto uses his Transformation Technique to transform into Shū. When Shū is able to re-enter his body, he asks who Shikamaru is and Shikamaru explains the mission to him. Meanwhile, before Chōji can win the final round of the eating contest, Shikamaru uses the Shadow Imitation Technique to stop Chōji from eating the last BBQ chicken, landing him in second place after Isono.

Trivia

 * The outfits Naruto and Chōji wear for the eating contest are the same clothes they wore during their childhood.