I have a calc request. So, I watch brightburn last night, and near then end of the movie, Brandon Breyer Flew from his home to the stratosphere (area above clouds) In 3 seconds. How fast would that be?
So, I imagine that you are working on the speed thread for One Piece, I don't know your opinion about FTL in OP, but I believe that you as well as others disagree with that until some character appears at the end of the manga, actually surpassing Kizaru's speed.
Anyway, I calculated a WB's feat reaching FTL+, I know it can't be used now but probably in the future, so I want to share it with you.
Fair, although there's a problem with one of the elements you use, and that's the distance used to get the timeframe.
We know that Kizaru started moving, however, we don't see where Shirohige started moving in relation with Kizaru's movement. On the other hand, you're using the particle's length to angsize which isn't possible. Angsize requires an horizontal/vertical line with known measure, and the perspective of the particle has depth because it's getting away.
This calc requires a specific distance that Kizaru travelled. In other words, we need to know the point A (where the move started) and B (where Shirohige stopped him). Without this, the calc falls on a lot of assumptions and is prone to fail.
You're also using the full lenght of the Murakumogiri, while you should use only the part where Shiro holds the blade and the blade itself (just by eyeballing from the scan you used to calc it, roughly a 1/3th of the full length). The rest of it is covered by Shirohige grabbing the bisento.