Fantasia: The Realm of Thanos

"Please save Fantasia!" a woman asked you. She's in front of you, a lonely girl who does not have anyone, asking you to save an unknown world from an impending doom by obtaining a heart key from one of four "heart bearers" The first one is a Demon Lord.... The second is a bloodthirsty assassin... The third is a mysterious hooded guy... And the fourth... has curse placed on him...