[1][2] Maruoka joined Borussia Dortmund in January 2014 on a one and a half year loan from Cerezo Osaka.
Liga with the club's reserve team on 25 January 2014 against SpVgg Unterhaching.
[3] Maruoka joined newcomer K League 2 club Gimpo FC in december 2021 after a season in BG Pathum United.
Mitsuru's brother, Satoru plays for ReinMeer Aomori in Japan Football League.
This biographical article related to a Japanese association football midfielder born in the 1990s is a stub.