Picked up a Beautiful, Strong and Miserable Killer

(Martial arts + swordsmanship + group portrait + single female protagonist) The story begins with a killer who was picked up from a grave when he was seriously injured and on the verge of death. He stayed at the girl's invitation and ushered in a life of fighting and fighting every day. However, everyone has a past that cannot be let go. When the conspiracy surfaces, who is planning the world, who is the chess player, and who is the chess piece? When war breaks out again, should each of us work together, or should we go hand in hand?