Zaicil Wrote:あと拾伍日
...after the 15th day?
-shrug-
edit: it seems to be written... -old-like, I've never seen 15 written like that and I've studied Japanese for 5 years.
Maybe I'm just stupid, could be. 
Edit 2: I cheated and put メイプルストーリあと拾伍日 in Google Translate:
"After Sun XV maple story"
or just "After Sun XV"
Yeah, it's ancient ways of writing the Kanji, but interestingly enough, they're still Kanji relevant to today - in legal documents, that is.
壱 = 1
弐 = 2
参 = 3
肆 = 4
伍 = 5
陸 = 6
漆 = 7
捌 = 8
玖 = 9
拾 = 10
The fact that they're using "ancient" Kanji for numbers tells me it's definitely going to be something from ancient Japan, whether this is a Jipangu (probably another past area like Kaede Castle or an expansion to Kaede Castle) expansion, or if it's a new class. With the fact that two (three) other versions are getting their own exclusive classes, it's likely that will be what we'll get in JMS. Maybe they'll tack on an area with it.