Excellent question!
Right now there's an event going on and you collect Mochi
which can be redeemed in the shop for event exlusive rewards.
You can also use said mochi to purchase Keys and Treasure
chests.
When you collect both a key and a treasure chest, you can
unlock them for a random reward. Bronze = Common items, Silver =
Common to Rare and Gold being Rare to Legendary "collectable"
items.
Unfortunately I do not yet have the "gacha" game online, but
it's in the works. Rest assured that everything you earn now will
be redeemable later with no expiration date even after the event is
over. The estimated time when the gacha game will be made available
is next week "sometime".
Schedule:
(Next week)
Next: New General / J-Spot design with feature support
After: Gacha game
(Week After)
After that: Remainder of the new design added to the rest of
the site
(Soon after)
After that: More features including Theme support. (People
with the X-Mas theme and the Cherry Blossom theme from this event
will be able to use it by this point)