Jirou walked away from his life as a hitman after his own country turned on him, and came home to Japan numb to everything. He had been one of the best wallmen in the trade: assassins who use climbing gear to scale buildings and strike from vertical positions no one else can reach. Then he meets Nami, a wallman still working, hunting down the people responsible for her father's death. Helping her pulls Jirou back into the underworld and gives him a reason to care again.