Lunin has joined on a season-long loan.
"I am physically well after a good pre-season," he said during his presentation on Wednesday ahead of his team's LaLiga season opener against Real Betis.
"Coach [Zinedine Zidane] decides who stays and who doesn't.
"I did everything to show my level this pre-season, but for me it is important to play and for that I am happy to be here.
"I want to thank Real Valladolid."