*Club domestic league appearances and goals, correct as of 23 February 2025, 14:20 (UTC) ‡ National team caps and goals, correct as of 19 November 2019
Yamaguchi began playing football in the third grade, playing mostly as anattacking midfielder. Upon entering junior high, he participated in trials with theCerezo Osaka,Gamba Osaka andKyoto Purple Sanga youth academies and ultimately joined the Cerezo Under-15 team, from whom he received an invitation on the spot. He enjoyed steady progress at the club, being selected to be part of the first entering class of theJapan Football Association Elite Program at the end of his first year. In 2006 Yamaguchi was promoted to the Cerezo Under-18 team, which later won the JFA Prince League U-18 in the 2008 season, in which he served as captain and was named league MVP.
Along with academy teammateYusuke Maruhashi, Yamaguchi was promoted to the senior team in 2009, spending three months of the season training with thePalmeiras Under-21 academy. He was named to the Japan Under-21 team in his second season and played in all of the matches in a gold medal campaign at the2010 Asian Games inGuangzhou.
Yamaguchi began to receive substantial playing time with Cerezo in 2011, scoring his first league goal on Matchday 24 againstUrawa Reds. The addition ofFábio Simplício resulted in Yamaguchi being increasingly deployed as anattacking 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 withTakahiro Ogihara in central midfield for both club and country, and being named to theUnder-23 team.
On 21 December 2015,Hannover 96 announced that they signed Yamaguchi.[3] Yamaguchi played for Hannover 96 in 2016, however returned to Cerezo Osaka mid-season.
On 19 December 2018, Yamaguchi sympathized with the goal of seriously aiming for the J1 League and AFC Champions League and officially completed a transfer toVissel Kobe[4] (later, he achieved the league championship as his goal). According to the media, it was a three-year contract with an annual salary of over ¥100,000,000, totaling over ¥400,000,000.[5]
In July 2013, Yamaguchi received his first call up to the seniorJapan side byAlberto Zaccheroni for the2013 EAFF East Asian Cup, where he played in all three matches and was named tournament MVP.
