The Last Revolver by GUMI. I'm not exaggerating when I say this song can make me cry.
To those that can't follow along without subs, basically GUMI is a bad guy and the other guy is on the side of good. Without meaning to, they fall desperately in love, yada yada. Then GUMI gets told she has to kill him. She's conflicted, but in the end, she does shoot him. Even though it kills her inside. And he forgives her.
I have a personal suspicion that that last gunshot at the end is GUMI shooting herself because she can't handle the thought of being without him. Your thoughts?
(This song makes me so sad though.)