is one piece episode 515 filler?

The episode starts off with an island called Kenzan Island, home of the Tehna Gehna Kingdom in the Grand Line. A group of people are gathered to see some kind of freak show which turns out to be just Brook.

Brook is holding a newspaper while the crowd is booing because he will not move. He will not move because he is remembering what Luffy had done for him and what he can do for Luffy.

He has a flashback of when he first met Luffy and remembers how Luffy wasn't scared of him and how Luffy wanted Brook to join the crew.