[1] He was the mixed doubles gold medalist at the 2013 Asian Youth Games partnered with Akane Yamaguchi.

[2] Koga was part of the national junior team that won the bronze medals at the 2014 Asian and World Junior Championships.

[5] Mixed doubles The BWF World Tour, which was announced on 19 March 2017 and implemented in 2018,[6] is a series of elite badminton tournaments sanctioned by the Badminton World Federation (BWF).

[7] Men's singles Men's singles Record against Year-end Finals finalists, World Championships semi-finalists, and Olympic quarter-finalists.

This biographical article relating to Japanese badminton is a stub.