Tsugumi Project 2 (manga)

In the western Pacific Ocean floats an island archipelago, cut off from the world and full of mysteries: scientific secrets that some believe are best forgotten, decaying monuments to an era of human decadence two centuries gone, and strange, radioactive monsters that tear apart any human beings foolish enough to set foot there. Its name, spoken only in whispers: Japan. An experienced soldier of fortune, Leon is tasked with retrieving a powerful weapon called Tsugumi.

Can they stay alive long enough to find this Tsugumi? And does it have anything to do with the quiet, brutal girl with taloned feet who swoops in to save Leon's life?