No, they won't. The subjects (hishiro and arata) will remember their re-life life. But others (kairu, oga, n others) will forget about hishiro and arata.
Just hope that after the experiment, somehow they'll find each other again.
Of course they will remember their re-life life, but still anyone who included to this re-life project will forget the subject. And both hishiro and arata are subjecs and they involve each other re-life life. So normally they will forget each other bacause of that.
So, Just hope they will meet again each other when they back to their normal life.
Remembering their future that they will forget each other makes me cry ╥﹏╥