Not sure who the other guy is... He doesn't look like Yuga's dad (who's a trainer at Saga Racecourse) and looks too old to be the Mirco expy from S3 of the anime (c/f post #6785480; for context Mirco was Loves' main jockey for a while)...

Jnglmpera said:

Not sure who the other guy is... He doesn't look like Yuga's dad (who's a trainer at Saga Racecourse) and looks too old to be the Mirco expy from S3 of the anime (c/f post #6785480; for context Mirco was Loves' main jockey for a while)...

Artist indicated in a follow-up comment that he's intended to be Mirco Demuro.

Apassingphantom said in twitter #1908399715131298227:

どこかの世界線ではネオユニやドゥラのトレーナーやってる人ですね。