Demon: Nyarlathotep
Requirements: Shining Trapezohedron
When Full Moon hits, between 0:00 and 6:00, approach the large tree in Nakano towards the south, and your Trapezohedron will shatter, summoning the Fiery Three-Eyed Nyarlathotep field boss, along with a mob of Deformed Black Oozes.
Once they're all down, there's a 20% chance that a second spawn will appear, with the Creeping Chaos Nyarlathotep field boss accompanied of a mob of Fiery Three-Eyed Nyarlathoteps. The Creeping Chaos Nyarltahotep drops a Kingdom Shard, a non-trade item. You need to take this Shard to the Junk Collector in Souhonzan and offer to show it to him, and he'll give you the Nyarlathotep Plugin: Crawling Confusion in exchange.
Guardian of the North