Infiltration: The Set-Up!

is episode 171 of the original Naruto anime.

Synopsis
While in the beach, Anko, still unconscious, is being tended by Ino. Meanwhile, Naruto explains his encounter with Isaribi earlier. The episode continues back into Anko's sudden remembrance of her memories. She sees Orochimaru approaching her, telling her that the Hokage knows about their experiments. Shino, Naruto and Ino decided to continue their original mission: To protect the official payments and capture the Kaima (Isaribi).

The group heads to Demon Island (Kikaijima), an island located in the Land of the Sea where supposedly the Kaima resides. Anko awakes and explains that the Kaima (Demon of the Ocean) is a human who has undergone physical transmutations. While they are talking, Yoroi and Isaribi head underwater to Orochimaru's lair. Inside, Isaribi passes on the information relating to the official payments and asks when she will return to normal. Yoroi tells her that she is a prototype and when he is done collecting information from her, he would change her back. He also sends her to dispatch Naruto and the rest of the group who has just arrived on the shore.

Shino, Naruto and Ino find themselves in an experimental laboratory with many creatures contained in test pillars. Isaribi approaches from behind and triggers a trapdoor. The three Genin fall through the trapdoor and Anko appears behind Isaribi with a kunai at her throat. Isaribi gets away and leaves Anko locked in the room facing three large lion-like animal mutations. Anko makes quick work of the three, only leaving the curse mark to pain her.

The rest of the team faces Yoroi Akado, who is working for the enemy. Shino takes up the challenge while Naruto and Ino continue running to catch up with Anko. Anko, Naruto and Ino find themselves facing Amachi and Isaribi. Amachi and Isaribi run off just while Misumi Tsurugi comes to face them. Ino uses her mind manipulation jutsu to restrain him. Shino's opponent disappears as the island begins to collapse. Isaribi, Amachi and Yoroi escape on a ship, leaving Team Anko to die in the collapsing building. Naruto frantically searches for an exit.