The title says it all.

Ruth has been raised to devote her life to a league of demon assassins called the Children of Rage, who murder innocent people with the twisted idea of maintaining the peace by preventing overpopulation on earth. But when Ruth is sent on a special mission to murder a boy that she has fallen in love with, and she is the only one who knows of the conspiracy behind all of the assassinations, she is forced to make a choice between who she is, and who she wants to be.