Calm down, Genndy. I'm pretty sure the message is from the refic story that I wrote. Here's the description of the letter that appears in the story:
It was addressed to someone with a strange name, who seemed to be a good friend of
my neighbor’s, but who hadn’t seen him for some years. It described his life over the course of
the previous year, and referred to other, preceding letters, for information going further back.
It ended with, “I wish I could hear of your children. By now they must be accomplished and
respected. I should hope they’ve surpassed their father by now. I can’t say he gave them much
of a standard to hold up. Still, at least one of us has a family to carry on his legacy, eh? There
are times I regret not finding a wife, but then the sea calls to me and I remember that I’m a man
who answers to no one but his own ambitions. Of course, I say ambitions where you might say
greed, but that’s a matter for another discussion. I end this letter, as I end all of these, by saying
you were the best friend a man could hope to find, and I don’t regret a thing about the time we
spent together. Your faithful friend,
Long John Silver”
I wrote the story with the intention that LJS would be able to contact Gulliver, sending him a final message, since Mr. A said it would be possible for a message to permeate one story and enter another. This was how I tried to make it up to LJS that we ripped Gulliver from him. So he sends out lots of messages in bottles. It's possible that the one Sayu found is not the one I described in the story, but they all probably have similar elements. If you want to know exactly what was written in the entire letter, I'm sorry, but I declare Death of the Author on this one.
Personally, I'm thrilled to hear that a message made it here. It means that at least one of them did manage to exit Silver's story, which means there's a good chance that at least one of them made it to Gulliver's story.