is one piece episode 523 filler?

The episode opens when the Caribou Pirates find the fake Straw Hats. Caribou attacks Drip (fake Sanji) and fake Sogeking subsequently tries to save him, but to no avail as Caribou has Logia-type Devil Fruit powers.

Coribou, Caribou's brother, is digging graves with the rest of the Caribou Pirates. In another scene, Rayleigh remembers when he first met Gol D.

Roger, a thought which causes him to shed tears; saying that the Straw Hat indeed looks even better on Luffy. Meanwhile, Sentomaru is seen reporting through a Den Den Mushi.