上原浩治
Koji Uehara was his teammate in high school. In that time, Tateyama was an ace pitcher and Uehara was an outfielder. In the 2011–2012 offseason, the Rangers signed Japan's best starting pitcher Yu Darvish to a 5-year deal. Tateyama and Darvish were previously teammates for 5 seasons on the Hokkaido Nippon-Ham Fighters.