This was mine! The title is "Price of Relief" referring to the anime's plot. It's about a girl whose puppy was hit by a car when she was a little girl. The girl never found relief and years later "Shounen bat" appeared who found and hit desperated people, but all the victims said after the attack, Shounen Bat brought them relief. After the girl facing her past, the guy with the bat also disappeared.
Too bad the anime was not released in HD, and I also colored the source, so sorry for the quality :/