That said, a-ra-shi now has an official "sister" community on DW for everybody who's moving there!
(don't even ask, of course the name pun is intentional)
There's also a community for Arashi fanfiction, for the people who are interested in that:
Both communities are ready to go, and you can go ahead and post there normally (stop asking if you can join LOL just click the "join" button! it's the same as this community!), but there might be some more tinkering done in the near future (especially with the layout).
That said, a-ra-shi is not going anywhere, so don't be worried about that if you're staying here on LJ.