To protect the peaceful life he shares with his beloved family, he steps back onto the battlefield once more!

To gather information on the mysterious X (Slur), who operates in the shadows, Sakamoto and Shin begin an undercover investigation at the JCC.

Meanwhile, Nagumo, Shishiba, and Osaragi of the Order head to Kyoto on a mission, only to be ambushed by an unexpected assassin...!

As conspiracies unfold, the intertwined pasts of a young Sakamoto, Nagumo, Rion, and X (Slur) are finally brought to light.