The breakthrough yearThe year he turned 18, the high school pitcher said at a news conference that he wanted to start his pro career in the United States.
The year he turned 19, he debuted for the Nippon Ham Fighters and made his first pitching appearance in May. The year he turned 20, he became the first player in Japan’s professional league with 10 wins and 10 home runs in one season. The year he turned 21, he struck out 10 in the opening game of Premier 12. The year he turned 22, he threw the fastest pitch in Japanese baseball history and was named Pacific League MVP.
The year he turned 23, he chose the Angels. The year he turned 24, he singled in his first MLB at-bat and won AL Rookie of the Year. The year he turned 25, he became the first Japanese-born player to hit for the cycle.
The year he turned 27, he was the unanimous AL MVP. The year he turned 28, he joined Babe Ruth as the only players with 10 wins and 10 home runs in one season.
The year he turned 29, Japan won the World Baseball Classic, he led the AL in home runs, won a second MVP and agreed to a 10-year, $700 million deal with the Dodgers.
The year he turned 30, he became the first 50–50 player, won the World Series and took his first NL MVP.
The year he turned 31, he pitched for the Dodgers for the first time, won a second World Series and a fourth MVP. The year he turned 32, he passed Ichiro Suzuki for the longest on-base streak by a Japanese-born player.
Shohei Ohtani debuted in 2013, the year he turned 19, and became known on Oct 21, 2012, the year he turned 18.
Ages are by calendar year (the year minus the birth year), birthdays aside.