Oh also, NeonBlack, do note that the epitaph is its own complete puzzle thats perfectly solvable. There's only one piece of information that the characters have that you don't, and its decently guessable. It does however require both knowledge of Japanese and English to solve, which made it just as hard for the Japanese to solve as it was for us.

If you wanted to take a crack at it, with its full text you have most of what you need to solve it, though I don't believe that anybody on the internet figured it out till after some clues we got in EP4.

I certainly didn't get anywhere close to solving it on my own, but then again I can't read Kanji at all so . . . I did side with the correct interpretation when it showed up online though.