魔女も歩けば悪魔に当たる

In a certain place there was a girl who aimed to become the best magician in the world.
As the start of her plan to fulfill those noble ambitions she summoned a demon.

But the world isn't that simple.
Despite the trouble she took to summon him the demon refused her demands and furthermore claimed that he would take her soul in seven days as reparations.

The girl was very surprised. Trying to negotiate by giving him money or someone else's soul was impossible.