So, we got this response now: "Dear Ninjas,

We'd like to inform you on the new rules on "Great Ninja War". The amount of battlefields open in Great Ninja War are related to the amount of participants. When participants are fewer, the number of battlefields will also be adjusted and less battlefields will open (this process depends on the number of participants of the last 3 weeks).

Naruto Online Support Team"

Ok. Now, would be awesome if we were informed about things like this before such changes are add to game. I mean- it kinda does look like people working on this game in this version have no idea what each patch contain o.ó

Prove me wrong: it was the same with group summons, that just happened to pop up in game with one patch and nobody had idea about it.