Yeah, that's the 2* chest. Although in my last run it gave me an Ampy instead. XDSomeone pointed in event page in response to my math wall of text that the random RNG chest in Ultimate map is a normal chest aka one that drops (for me at least) only 2* girls, not dumplings. I run that map few times and actually got that chest each time so can someone else confirm that? I rather run Advanced map for a bit more exp as with my 6* and 5* drop luck I will probably have enough crystals from daily quests alone XD (a.k.a. my only reliable source of 5* are events and reissues). (EDIT - checked it myself it is not dumpling dropping chest, neither it is life crystals one - so static 0.5 ratio for dumplings and no RNG there, no RNG for crystals, only RNG for that chest that drops a 2* girl most of the time /EDIT).
If its true I will need to edit few of my posts to remove misinformation from them.
Also in last event at least in Advanced map (which dropped 2 crystals), I got once or twice a 3rd crystal. Not sure if 2 bonus ones mentioned in few posts above is wrong, or is it 1 or 2 and I was unlucky in luck of getting bonus ones, or is it about this event (didn't get lucky yet in this to get more than basic 2/5).