Eugeo is a fictional character from the light novel series Sword Art Online: Alicization, written by Reki Kawahara. He is a skilled swordsman and a close friend of the main character, Kirito. Eugeo plays a significant role in the story, helping Kirito navigate the complex world of Underworld. In the series, Eugeo is initially a Cavalry apprentice tasked with maintaining order in the Underworld. He possesses a strong sense of justice and loyalty, which drives him to fight against the oppressive system governing their world. His character development is central to the themes of friendship and personal growth throughout the narrative.