Gungho has officially released details about the Batman collaboration that was discovered in some of the downloaded files in the most recent update. It will be a promotion for the soon to be released Batman Arkham Origins game. The collaboration will run from 10/30 at 12:00 through 11/13 at 11:59 Japan time.
There will be a dungeon, which seems to be only 1 battle against the Joker, but it will have 4 difficulties.
In addition, there will be a Batman rare gacha featuring 5 Batman characters, some of which you can see below. The page also notes that during the 20 million download event all of these rare gacha characters will be plus eggs (through 11/4).
The 5 characters will be:
– Batman and S-Glove (dark/light element)
– Batman and Batwing (dark/water element)
– Catwoman (fire element)
– Robin (wood element)
– Batman and Batarang (dual dark element)