"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 doom by obtaining a heart key from one of four "strong boys". You decide to do the task, but......
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...
To obtain the key, there are those who will try to stop you, a shy maid, a happy-go-lucky elf, a lonely demon, and also the bearer of the ultimate key...
...Oswald Leingold.