I am in a bing /wsr/ I forgot the name of a manga I really enjoyed.

It was really short and rushed but the art was nice. The main character was a standard black haired guy, he was a falsesly comitted prisoner who was tasked with digging graves. Then they were involved with this blonde girl who had to fight the monsters and lose so they would die and be buried to stay dead. Can anyone remind me what the name of it was pls