thinking_hat.jpg
[Hide] (503.3KB, 2026x2865) gensokyo.jpg
[Hide] (2.8MB, 1920x1080) What did he mean by this?
Hmm...
Going by Gensokyo geography, I'm assuming the mountains is referring to Youkai Mountain, where the kappas lie at the base thereof. The shores that share its name refers to the Youkai Forest. To the west of it is Tengu's Mark, with the key between them. Tengu's Mark may refer to the Untrodden Valley, though I'm not sure about that.
Now, with that out of the way, the twilights each refer to the times between day and night, obviously, so probably around 18:00-20:00. The Five Chosen are probably the Tengu's enemies: Weasel aka HangingFlesh, Dolphin, the schizo tripfag, Nepfag, Mark and Tewifag. Now there's six listed, which probably means that either the schizo tripfag is irrelevant, or Weasel and Dolphin are counted as one under /cow/. So I assume by sacrificing them, we do a little trolling, twice.
Then, we deflect the inevitable counter-attacks (or any accusations that it was teenbros), then we read the mentioned threads and 'kill', probably meaning to kill the threads. The pill for Meta maybe means redpill (tengupill in this case). The final night, where secrets will be revealed, probably means the Great Tengu reveals some big and juicy secrets to the world.
With this, the fires of /japan/ are lit brightly forever and ever.
But this is all speculation on the part of an autist on his free time. Add your own opinions or speculations if you want.