is one piece episode 15 filler?

As the Usopp Pirates come to his aid and beat Kuro as he is down, but Kuro gets up and beats Usopp to the ground. Now knowing his opponent possessed a Devil Fruit ability, he decides to personally focus on Luffy, ordering Jango to pursue and kill Kaya.

Although now incapacitated and no longer able to fight, Usopp orders the children to protect Kaya as she evades Jango's pursuit. Although Zoro attempts to aid Luffy, he is stopped by a strengthened Buchi.

Although Buchi greatly disrupts the battlefield with his powerful attacks, Zoro uses his three swords to cut him down.