if you're wanting to buy the tickets, tu can't. Tickets have been sold out for maybe a month. But, tu can prob check ebay. Maybe some people are selling them for over priced there if tu really want to go. But do tu really want to risk your hearing?
There will be so many fangirls there. The room fits a certain amount of people, but I'm sure the fangirls will pack in. Plus they'll be screaming, and if tu don't get a good seat, tu won't be able to hear anything. If tu get annoyed easily, especially with the fangirls, I suggest just watch a live streaming video if they have them online.