Once upon a time there were two races; Humans and monsters
Monsters were locked underground with a spell that could only be broken with 7 human souls.
6 humans fell.
6 souls were collected.
However the last soul was the trickiest to collect.
Every time their soul was collected, they would go back to before that moment.
They would stop their soul's collection.
Their soul would grow more DETERMINED every time.
Slowly they befriended each monster for the sole purpose of getting out.
After all, they had one person they needed to SAVE.
But when they did get out, they were yanked back to the very beginning.
They tried again.
They started again.
They tried again.
They started again.
However every time they started, they noticed their soul did not RESET.
And so every time they started again, they killed a monster. Just one.
And finally, at their soul's peak, they broke the limit. They went to level 21.
And at level 21, when they RESET, so did their memory.
And they forgot who they were protecting when they left their house at dawn.