"Sasuke's Paw Encyclopaedia" (サスケの肉球大全, Sasuke no Nikukyū Taizen) is episode 189 of the Naruto: Shippūden anime.
Nekobaa is visited by a cat, who sees a photo of Team 7 and makes remarks about Sasuke. In the past, Nekobaa had hired Team 7 (minus Kakashi) to collect a pawprint from Nekomata, the ruler of the ninja cat underworld. Because this was originally a mission Itachi had bequeathed to Sasuke to test his strength, Sasuke decided to complete it to prove that he could surpass Itachi's expectations.
As they visited Nekobaa, Sasuke was infuriated by the mention of Itachi's name. Nekobaa explained to Naruto and Sakura that Itachi had tasked Sasuke with capturing feline paw prints before, which she compiled into a Paw Encyclopaedia. The three genin were assigned to break into Nekomata's fortress to acquire his pawprint and were given Cat Ears to not only deceive other cats into thinking that they were cats as well, but to be able to understand cat speech as well. As Naruto lost his cat ears, Sasuke and Sakura sneaked in undetected and split up to cover more ground. Sasuke easily defeated all of Nekomata's bodyguards and made his way to face the ninja cat, who placed Sasuke within a genjutsu. Using his Sharingan, Sasuke managed to break out of the genjutsu and dodged most of Nekomata's attacks. As Nekomata was about to crush Sasuke, he was saved by the arrival of Naruto and Sakura. However, Sasuke told them that this was his mission and that he did not need help. Revealing that he had placed explosive tags around the ceiling, Sasuke detonated the tags and buried Nekomata under rubble, acquiring his pawprint.
Nekobaa muses how cute Sasuke was then, while the cat she is talking to is revealed to be none other than Nekomata, who was asked years earlier by Itachi himself to fight Sasuke when the time came. As Nekomata glances at a photo of Sasuke and Itachi gathering their pawprints, she remarks how they used to be so close to one another.