He enjoyed steady progress at the club, being selected to be part of the first entering class of the Japan Football Association Elite Program at the end of his first year.

Yamaguchi began to receive substantial playing time with Cerezo in 2011, scoring his first league goal on Matchday 24 against Urawa Reds.

The addition of Fábio Simplício resulted in Yamaguchi being increasingly deployed as an attacking midfielder toward the latter part of the season, which he finished with 30 appearances.

He followed up by winning a regular position on the Cerezo side in 2012, combining with Takahiro Ogihara in central midfield for both club and country, and being named to the Under-23 team.

In July 2013, Yamaguchi received his first call up to the senior Japan side by Alberto Zaccheroni for the 2013 EAFF East Asian Cup, where he played in all three matches and was named tournament MVP.