Hmm, very interesting, an IA concert during my stay in Japan, but not only did I already play to be somewhere completely different, they don't seem to care for any foreign attendees at all compared to the Miku concerts, Japanese application only it seems like!
I don't think I wanna see IA that bad as to spend a lot of money on the ticket plus a proxy thing.
EDIT:
Since OP didn't provide a link, for anybody more willing to spend money on effort:
1st PLACE創立15周年を記念して、国内初となるLiaとIAによる一夜限りのスペシャルライブが開催決定。 (Link to the article and Japanese with information)
Lia/IAのチケット情報(東京都)|e+(イープラス) (This seems to be where to get tickets)
Also made some quick research and the arena in Tokyo seems to be tiny, having seats for a bit more than 800 people. Maybe that's why they don't really care and don't even try to get foreigners interested. A shame though, since 1st place certainly did try to expand globally moreso than even Crypton from time to time.