This time around it took me less than 10 attempts to finish the fight for the footage you see here. Slowly getting there. Like most spear-wielding enemies, you heavily benefit from using the Mikiri Counter against this one. In the case of the Seven Ashina Spears, whenever they are swinging their spears above their heads to wind up for a strong knockback attack, you have the opportunity to get 1 or 2 hits in. If you struggle with this miniboss and need a fast path to get over to him from the Ashina Reservoir idol, then I can recommend going left at the start to swing over to the other side of the area using your grappling hook. Kill the small lad with his alert-gong before he can make a sound and from there essentially take the route you did at the very start of the game. This eliminates the necessity of having to kill all enemies in the area before facing off against Yamauchi. Be careful though not to get too far down the staircase where he resides, since enemies can still spot you, like they almost did spot me.