is one piece episode 352 filler?

Brook runs up a flight of stairs, and confronts Ryuma in a room, calmly waiting for him there. Ryuma asks if he knows what giving up means, to which Brook replies he will never give up until he reclaims what he has lost.

Ryuma states that he is a legendary dragon slaying swordsman and that the level of their bodies are different, but Brook disagrees, saying that he is his shadow and will fight to return him to his rightful position- under Brook's feet.