The left back joined the Tynecastle side in the summer of 2015 and amassed a total of 24 appearances in all competitions in his first season.
But the former Ashdod defender has seen things change drastically this season as he is yet to make an appearance under Ian Cathro.
"Things change quickly in football and I can only keep on fighting to get my chance," Oshaniwa told BBC Sport.
"People have been asking me what's going on in Scotland, and the only explanation I can give is that - this is football.
"When I joined up with the Nigerian squad in England [last month] it's the same question but I believe with hard work I'll get another chance."
"I can't give up. I know giving up is not an option so I'll keep up the fight.
"I still want to represent my country and its only regular football at my club that will earn me regular call-up."
Hearts are fifth in the Scottish Premiership table as they have garnered 41 points from 29 games.