Tanaka's first major international competition was the 2009 World Championships, where he qualified 10th to the individual all-around with a score of 86.650. In the final, he placed fourth with a score of 88.300, a tenth of a point behind third place. He won the bronze medal in the parallel bars final, scoring 15.500. Tanaka competed for the Japanese team which won the silver medal in the team-all around competition at the 2010 World Championships, contributing scores of 14.166 on still rings, 15.483 on parallel bars, and 14.433 on high bar. His team matched this feat the next year at the 2011 World Championships, where he contributed scores of 15.500 on parallel bars and 15.141 on high bar. He also qualified seventh to the parallel bars final, and placed eight with a score of 15.166.