Through to the End.
Four years in the past, a young Shin searches through an old battlefield before finding Shourei's headless corpse. In the present the Legion begins rapidly evolving its tactics to counter Spearhead's ambushes, and Spearhead suffers two casualties, Daiya and Lecca, in their latest battle. Shin is forced to mercy kill Daiya to prevent the Legion from harvesting his brain. It's revealed that Shin is focused on finding Shourei's missing head, and that Shourei attempted to strangle him in the past in a fit of rage, blaming him for the deaths of their parents...