Koroki was born in Miyazaki on July 31, 1986. After graduating from Hosho High School, he joined J1 League club Kashima Antlers in 2005. He played many matches from 2007 and Kashima won the J1 champions for 3 years in a row (2007-2009). Kashima also won the champions in the 2007, 2010 Emperor's Cup and 2011, 2012 J.League Cup. He played 192 matches and scored 49 goals for Kashima in 8 seasons. In 2013, he moved to Urawa Reds. Urawa won the 2nd place in the 2014 and 2016 J1 League. In Asia, Urawa won the champions in the 2017 AFC Champions League and the 2nd place in the 2019 AFC Champions League.