He was a member of the committee and was responsible for maintaining the Duel Carnival along with his friend, Dextra. He was also searching for Number Cards. He is very honorable when it comes to dueling and sought to punish anyone who tried to cheat. When he caught Flip cheating, he ran into Yuma who tried to defend his friend. Nistro and Yuma ultimately dueled but Yuma was able to defeat him.
Now determined to battle Yuma again, Nistro resigned from the committee and joined the Duel Carnival but lost to Yuma in an honorable duel. Nistro and Yuma become good friends because of this.
In the second series, Nistro becomes a Pro Duelist in Spartan City and takes the name Nitromo the Star Voyager, and makes a costume (picture above) to inspire and give hope to children. He becomes an ally to Yuma in his fight against the Barians.