For the Family That Chose Me - Dramabox

On the run from assassins, Evan Zeller—the sole heir to Zeller Corp—falls into a raging river and loses his memory. Rescued by a kind couple, he assumes a new identity as "Hayden Hoover" and works tirelessly to become a top achiever. Just as he’s about to repay his adoptive parents, his biological grandfather finds him and whisks him away for intensive training.