This is a story related achievement.
The boss in this level is the Daimyo and he is the last person that you face in the stage. He’s a fairly simple boss who’s attacks you can parry when you learn how to do so in the middle of the match. He’ll strike multiple times, all you have to do is be able to parry his attacks which will stun him temporarily and then unleash any variation of combos using light and heavy attacks on him. Using in focus attacks to finish the combo is recommended because it does more damage.