Deep Silver and Grasshopper Manufacture worked on a PC version of Killer is Dead titled Killer is Dead: Nightmare Edition. This version includes all of the DLC missions, a new Theater mode, and a Nightmare difficulty level.
Killer is Dead: Nightmare Edition was released on Steam and in Japan it will also be sold in stores. E-Frontier is the publisher and Zoo is handling sales. While the game is on disc, it still needs to be activated through Steam.
Even if a game is developed in Japan, there’s no guarantee the PC version will be sold there. PC gaming is niche in Japan with the majority of releasing being visual novels. Falcom, for example, used to prioritize PC, but even their RPGs found more success when they moved to PSP.