Ep 1. Underworld

In Sword Art Online season 3 episode 1, titled "Underworld," the story follows Kirito as he enters a new virtual world called the "Underworld" that was created by a company called Rath. The Underworld is a world where the inhabitants are human-like AI created by a mass simulation system. Kirito's mission is to test the system's potential to be used as a new type of treatment for comatose patients. Kirito is one of those patients and has agreed to enter the simulation in hopes of finding a way to wake up from his long slumber.

As Kirito enters this new world, he finds himself in a quaint medieval village called Rulid. He quickly learns that the villagers have a long-standing tradition of a yearly pilgrimage to the top of a nearby mountain. Kirito offers to help the village prepare for the pilgrimage by participating in the village's annual sword-fighting tournament. He quickly becomes friends with a young girl named Eugeo, who is a talented swordsman, but is held back by his low societal status as a peasantry. Together, Kirito and Eugeo embark on a journey to climb the mountain and delve deeper into the secrets of the Underworld.

Along the way, the two friends encounter obstacles that challenge their strength and test their wits. They learn more about the AI inhabitants of the Underworld and the intricate political structure that governs their society. Kirito and Eugeo also encounter dangers from outside sources that threaten the peace of the Underworld. The duo becomes determined to protect the people of the Underworld and stop those who seek to harm them.

The episode is filled with action-packed scenes of sword fighting and exploration as Kirito and Eugeo journey through different parts of the Underworld. New characters are introduced, each with their own unique skills and backgrounds, and a complex political and social hierarchy is established. Throughout the episode, the story also delves into themes of friendship, societal order, and the nature of reality, making it a thrilling and thought-provoking episode.

Overall, the first episode of Sword Art Online season 3 provides viewers with an exciting and intriguing introduction to the new world of the Underworld. The episode sets up a promising storyline with engaging characters and a complex society. Fans of the show are sure to be hooked from the very beginning and excited to see where this new chapter in the Sword Art Online saga will lead them.