is one piece episode 772 filler?

Luffy expresses his excitement for the upcoming battle with Kaidou, and the members of the newly formed Ninja-Pirate-Mink-Samurai Alliance once again celebrate their formation. However, Luffy then brings forth a condition to their alliance, as he requests that he go rescue Sanji from Big Mom before the final war.

Nekomamushi remembers Sanji, but Inuarashi does not due to having been in a coma at the time, and Nekomamushi explains to him who Sanji was and how he left Zou.