If you haven't done it yet, the Japanese client has been updated.  You
need to update it from the App Store/Market and then download 2 more
rounds in-app, so it is probably better to do it early, because after
the event starts tomorrow the server will be quite busy.

They added some new functions, a task system that replaced some of the
game mechanics, and more stuff (backgrounds, titles, seals etc.) to
collect. There are also daily tasks you can complete for prizes.
(Note: When I completed the 3 level 1 daily tasks yesterday, a level 2
task that rewards a stone appeared.  Not sure if it is true every day.)

-- 
Stephen Lee <usagi@softmagi.com>