In a dangerous world, a guardian angel and a guardian demon were given to each person.

But the universe did not like you falling for Isagi and Michael. So it decided to punish you by taking them away.

To restore balance, you made a promise to marry a mortal and shut off your feelings for your guardians.

You begged the universe to bring back your guardians, and it gave you one last chance.

The universe warned that failure will result in their souls getting lost and dying forever.