I was forcibly summoned as a saint and had a terrible time, so I asked the demon king to use his power to send me back to my original world.

High school girl Tetsuko was summoned to another world as a saint while returning home with a friend. After being exploited and used up, she borrows the power of the Demon King to return to Japan. Her traveling companions cling to her in tears as she leaves, but it's too late. The kingdom must now face the Demon King's serious assault without the saint.