Seungcheol, Jeonghan, and Jisoo are like the sun, the moon, and the stars. Seungcheol lights up the world, Jeonghan brings it to rest, and Jisoo gives it comfort.

Then Jeonghan leaves for university.

When he returns, Jisoo is no longer the same. Long-term memory loss caused by head trauma, the doctor says. 

The stars are scattered, and Jeonghan doesn't know if he can string them back together again.