Answer
In his record-setting 2013 NPB season, Masahiro Tanaka did not lose a single game. He pitched 24 complete games and had a 24-0 record, leading the Tohoku Rakuten Golden Eagles to the Japan Series title. Tanaka's 24 wins tied the NPB record for most wins in a single season, set by Hideo Nomo in 1995. Tanaka also set the NPB record for most strikeouts in a single season, with 246.