"Saiyuki Gaiden" is a manga series that serves as a prequel to the original Saiyuki story. It explores the backstory of the characters, particularly focusing on Genjo Sanzo, Son Goku, Sha Gojyo, and Cho Hakkai. The narrative delves into their pasts, revealing how they became the individuals known in the main series. Set in a fantastical version of China, the story combines elements of adventure and mythology. It highlights themes of friendship, sacrifice, and the struggle against evil forces. The artwork and storytelling are crafted by Kazuya Minekura, who brings depth to the characters and their journeys.