What is the purpose of the Shinjuku Map item?

One of the items released via QR codes for Etrian Odyssey 4 is called the "Shinjuku Map." However, I haven't found anywhere in the game that uses the map. Is it possibly for content that isn't released yet (maybe a free dungeon kinda like how Fire Emblem has some free areas)? Or does it serve some other purpose?

Source (I just noticed the .html file name for that URL when I pasted it.. interesting. Related?)