Shuuji Tanegashima was first believed to be just another strong 2nd Stringer in the U-17 Training Camp. However, it is revealed that he was a member of the 1st Stringers and is the No.2 of the All-Japan Junior Representatives upon the rest of the Genius 10's arrival. He did not go with the team on their foreign expedition due to his hatred of airplanes.
Source: Prince of Tennis Wiki