It only gives 200. I was spamming it today to get some extra keys for the cave key rebate. It shows that you get 400 when you are in the Arena menu, but when you go to Grocery and look, you only get 200.

Also, for Sun Scrolls, it shows in game that we can get them from Shinobi Conquest and Rogue Ninja Outburst. What are those? They can't be Matsuri, Sage, 9 tails or Rescue - since those are also listed as places to get Sun Scrolls. Are they events that we never got? Future events?