>>20924478
I had half a solution worked out for the epitaph. I was focused on "sweetfish", which seemed a really specific translation for a kanji that could also have been read "trout" (I have no real knowledge of moon). I knew Kinzo liked western stuff, and I had the vague idea that the riddle was just wordplay, so I translated "sweetfish" into a bunch of euro languages, and in French I got "poisson doux", which could be mis-pronounced English-wise as "poison dose". There was only one "poison dose" I associated with Kinzo -- the stuff he kept drinking. Maybe "beloved hometown" was some Japanese metaphor for one's body, who knows.
I didn't really know what to do with following the river down, but using the same Ja->Fr->En trick, I got "key" -> "clay". So, I thought, maybe the floor somewhere was slightly tilted, and if you poured liquid, it would flow in a direction that pointed towards a secret room or trace a pattern. I wrote this off as "a clue which has not been fully hinted yet".
As to the ritual, I focused on "tear apart the two who are close", and thinking that it had something to do with the green alcohol, I got it into my head that the ritual was a set of instructions for a chemical procedure. Perhaps the second twilight was dissolving a salt, or something. "Gouge" could mean "stick into [the system] and stir", and "kill" might mean "discard the precipitate". Maybe there was an old alchemical system that would tell you want "knee" meant.
After I thought about that for a while, I realized that I could also explain how Kinzo had the astronomical amount of 10 tons of gold, and why it was so rarely seen. He didn't have 10 tons of gold in bar form, he had 10 tons of a solution that included dissolved gold, perhaps in an underground inlet that he had converted and sealed off. The epitaph was instructions for reconstituting it, but meanwhile he was drinking it and going mad.
I knew I was probably wrong, and as soon as the midpoint of Ep3 rolled around that became definite, but I still like parts of it.
I also had some ideas for getting around the early key puzzles by allowing extra master keys made out of wax, which melted before the red text prohibiting them was said.