Everyone had heard of the Gumiho.

But ever heard of her hoobae, Sibmiho, the ten-tailed fox?

Like her Sunbae, Sibmiho had always wanted to become human.

She knew exactly how from Gumiho, but she also know Gumiho's heartbreak when she finds out in order to become human, Daewoong must die.

Sibmiho NEVER want to go through what her Sunbae went through.

So if she lets a bad person inhabit her fox orb, even if he dies there is nothing wrong right?

She may even be doing good by getting rid of bad guys...

Right?

Kim Myungsoo is the most badass guy in Seoul. He fights,drinks and flirt. Part of the strongest gang Infinite. With their good looks, they are easily the kingkas at Woolim High.

What if a Sibmiho comes into his life and he has to live with the SAME girl for hundred days? (A gorgeous one but still..)

It is impossible for playboy Myungsoo.

As days go by, they start to discover good points about each other and slowly..unknowingly.. they fell in love.

How would they handle the day when it is time for Myungsoo to die?