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...