One day, after the incident related to the Killing Stone,
Natsu was tending the shrine alone when the mayor of a neighboring village approached her.

According to the mayor, his village was under attack
by youkai and gravely in need of an exorcist.

Unfortunately, Natsu was no exorcist, but a goddess...

She pondered this to herself before assuring the mayor
that she would still do all she could to assist them.

And so began Natsu's journey to the mayor's village
to eliminate the evil youkai once and for all.

[Taken from game manual]