Mart and Tetra

One day, me Tetra was walking in a dungeon.
I helped Mart, ex-Demon king by chance.
She took my body, so I was lost, but…

\”I will make you Hero. Let’s defeat the present Demon king with me!!\”

I was so weak that I dreamed of becoming a hero.
I decided to take the proposition of ex-Demon king to defeat the Demon king.

Me, who can’t fight but can save magic power, and ex-Demon king, who can fight but can’t save magic power.
Will we be able to defeat the Demon king in the end?​