Basically there's no news of an Ayu tour anywhere in the West for now... simply put. Maybe she will, maybe she won't? But like tasking said, a concert of two to start off is more likely, rather than a huge tour.
By the way, you know what was interesting... Ayu was listed in ticketmaster (I was bored one day). Of course no concerts are listed now, but her name is there haha, and you can sign up for her notifications.
http://www.ticketmaster.com/artist/7..._header_search