Amidst the hustle and bustle of Tokyo, AMO officer Natsuki Hyogo has had an unexpected encounter with Chizuru Sato, his friend since childhood and first love from his faraway hometown! While the feelings between them may be flickering back to life against a big-city backdrop, a threat looms in the form of a sinister alien that's hooked its claws into a clueless Chizuru. Desperate to protect Chizuru, Natsuki's journey will take him all the way back to the long-ago events that befell him, his mother, and his superior officer, Reiji Amamiya. What old ties and surprising connections will come to light?