Syrus Truesdale, known as Sho Marufuji in the Japanese version, is a character in the Yu-Gi-Oh! GX manga.
Syrus is a much better duelist than his anime counterpart, although he is hampered by his desire to not cause pain to his opponents. In the past, he had forfeited a duel when his friend was in tears, despite victory being in his hands, prompting his brother to consider him too kind to be a duelist. In the English adaptation, Syrus refers to Jaden Yuki as "bro" which is a play off what his use of the term "aniki" in the Japanese. Jaden questions why Syrus does despite them not being brothers, and Syrus responds that Jaden reminds him of when his real brother taught him do.
This version of Syrus considers this brother's lack of regard for his abilities as something to overcome, rather than proof of his inferiority. He is determined to be acknowledged as a good duelist. He ends up having to face Jaden in a duel in order to stay at the academy, and despite losing, the entire thing was revealed to be a mix-up. It was thought that Syrus had gotten a zero on a test, but it was actually Jaden that had failed. Syrus participates in the tournament to determine who will earn the right to face his brother, and he loses to David Rabb in the preliminaries. Despite this, he makes it to the to eight, but is defeated there by Chazz Princeton, who originally considered Syrus to be weak. Chazz ultimately wins the tournament, and later finds himself paired with Syrus against James Crocodile Cook and Axel Brodie in a Tag-Team Duel. Syrus wins them the duel, and he earns Chazz's respect in the process, with Chazz acknowledging Syrus as another rival he'll need to overcome.
Syrus would be matched against Jesse Anderson in the singles matches for the tournament. He gains an early lead, but Jesse defeats him with "The Tripper Mercury" after being briefly possessed by Tragoedia. He witnesses Jaden and Chazz defeat Tragoedia, and watches Jaden's match against Koyo Hibiki years later.