Mascarell is confident that he'll be returning to the Spanish capital once the season is over.
"The buy-back option is going to be exercised, but I do not know what will happen to my future," he said in an interview with EFW.
"I think Real Madrid want me to complete pre-season with them.
"I think they are interested in keeping me, but I would like to continue growing and gaining experience, so my thinking is to stay in Germany if I have to leave Real Madrid."
Looking back on his past with Real Madrid, he holds fond feelings for the club.
"I only have words of thanks to Real Madrid because during my stay in Valdebebas they improved me both from a football standpoint and a mental one," he said.
"They made me mature beyond my years and they taught me to always win."