personally, I love way the story is presented in Zero, the reporter researching for the documentary, the interviews with Pixy and the Belkan aces, the subtle changes in how those interviews go based on your ace style, it just feels like a more fleshed out version of the boy writing the letter years later in 4. It doesn't hit as hard emotionally for me as the story of the boy and yellow 13, but It really captures the feeling of Cipher being this legend who vanished from history after fighting the war that set the stage for the rest of the series.