Shitty writing or shitty animating. Up until now this guy has taken excessive amounts of punishment with no obvious ill effects, has punched people through doors, and deflected A MOTHERFUCKING BULLET WITH A SWORD HIDDEN IN HIS ELBOW.
And then, some ordinary looking woman throws some ordinary looking kicks and suddenly he's down for the count? NOT FUCKING BUYING IT. If they wanted me to buy this episode, I needed to see Shinkurou have some serious shit happen to him, flying through walls, blood spurting, etc; and it didn't happen. Not even close.