No mention of a lottery yet, but the general sale for G7 in October is listed now in eplus.

Details

Event:  Ｇ７　ＲＯＣＫ☆ＳＨＯＷ　忘れ歌を、届けにきました。
Location: Okinawa Music Town Hall
Ticket sale:  10/14/2017 @ 10:00
URL:  eplus