Demon: Lilith
You will need to head to the Shinjuku field (the map-less area to the Southwest of Shinjuku Babel), and find a teleporter that leads you to an alternate world. Once in there, you must Talk to a tall hooded woman called "The Shadow Chaser", who will give you the quest:Shadows in the TMG Building. Once finished, you will get another quest, titled Lord of the Flies. Upon completion of this quest, you will recieve the Lilith Plugin: Petals of Lily.
Crawling Confusion