Prior to Marineford, Kuma was the only RA who knew that Luffy was Dragon's son.
It's a good thing to know how he knows that when even Iva is clueless about it, it would have been a plot hole.
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I can't call the chapter mid when the main point of it is Kuma's letter, and we don't know yet what is its content.
Emotion Piece=Lore Piece>>Agenda Piece=Battle Piece>Funny Piece for me, so i'll wait.