The year is 1931, the 64th year of the Meiji era. The 15th Shogun, Yoshinobu Tokugawa, continues to wield absolute power thanks to complete monopolization of a special natural resource known as "Ryumyaku." Supporting the Tokugawa regime from the shadows are the deadly agents of the covert organization known as Nue.

It's become clear that Nue agents don't leave the shogun's service and live to tell the tale, so it's up to Asahi to find a way for Sawa to break free of the life of violence she's become trapped in.