Over millions of years past since Demise was sealed away and Ghirahim was pronounced dead. Our hero's soul, as told my Demise before he was sealed away, was cursed to fight the evils that threatened to take the power of the Triforce and was reincarnated every several hundred years when Evil began to strengthen its powers and threaten the lands.
Our hero has been through many hardships over the many years he lived and over his many lifetimes, but he does not remember any of his previous lives. No one does.
Evil now begins to once again strengthen and covet the Triforce and as always our hero is once again reborn. Unfortunately, his new life now will be one that could change the curse that is bound to his soul and destroy the lands that protect the whereabouts of the Triforce.