 When Ryu was 10, his father bought him a lefthander’s glove that goes on the right hand, so Ryu learned to pitch with his left hand.In 2004, Ryu underwent Tommy John surgery and did not pitch in any official games.In 2005, he led his team to the Blue Dragon Open National High School Championship, pitching 22 consecutive scoreless innings as the team's ace and batting .389 in the tournament.