Satsujinsha no Zaiakukan

"Guilt of the murderer"
Deidara has killed more people than any other member of the Akatsuki. He has killed thousands of people, including innocent women and children. Deidara is a hardcore killer, and he never shows remorse for his actions. Even so, he has killed people he wishes he hadn't. This is bound to have happened at least once out of all of his kills. Even killers have skeletons in their closets, and Deidara is a character with many, guaranteed.