Yoonhee ( you ) and Soonhee are twins. 

The both of you fell inlove with different guy. 

The 4 of you have different powers. Yoonhee- water. Soonhee- air. Sungyeol- electricity. Myungsoo- fire.

Then the time comes that your competitors arrived. Everything went upside down.

Your boyfriend died and next was your sister.

It only means that You and Myungsoo have to stay together in order to live.

But what if you found yourself falling inlove with him?

And was he prepared to love you back and forget Soonhee?