These are the main online ticket websites in Japan , general ticket balloting wise
e+
http://eplus.jp/
L-tike
http://l-tike.com/
Ticket Pia
http://t.pia.jp/
I don't know how the ticket system works in your country but in Japan , I think they're the only country in the world where the ticketing system is based on balloting & not on a 1st come 1st serve basis (which's the most common method used in my country and normally this means the online ticketing system will crash very frequent for the more popular English or non English artistes)
This means that you will be given a certain period of time to ballot for an artiste's concert ticket . Depending on the artiste or venue , you may be allow to ballot to up to 2 tickets or 4 tickets per person
Also it's not necessary you have to ballot for the maximum number of tickets . You can ballot for only 1 ticket if you're going alone
After the allocated time frame , balloting will be closed and then a few days later you will find out if your balloting is successful or not successful by email
If your ticket balloting is successful , you will be given a new time frame to pay and if for some reason you choose to forfeit or miss the payment deadline , the website might penalise you in not giving you a successful balloting application in the near future
Balloting is based on luck so it doesn't mean once the time allocation to ballot for tickets is open , you should immediately ballot for tickets . You could ballot tickets on the last day of the deadline but yet you still might win it
You wouldn't know the seat number immediately , you would only know about if your seat number is good or bad when the tickets are mailed to you 1-2 weeks before the actual concert date
If you don't want to go through this method , you can always try
http://www.ticket.co.jp/ or Yahoo Japan Auctions but usually for these , the sellers would tell you the ticket number upfront and normally you're expected to pay even more than the actual face value of the ticket cost
Also depending on the artiste , some are strict and might check the ticket particulars prior to allowing you to enter the venue so if you buy a ticket from a 3rd party , they might not allow you in
The reason why fans join any artistes' fanclub is to get better chances in scoring better tickets cos usually when the general sale balloting is open , by then the not so good / bad seats will be left while a considerable number of tickets are reserved 1st hand by an artiste's fanclub
But end of the day it really depends on your luck . You might ballot via the general ticket sale & your seat number could be even better than someone who balloted/got their tickets via the fanclub
If all else fails , there's always a small possibility to buy tickets at the door on the day of an artiste's concert , provided if they post online that they're still selling leftover tickets on the day itself . I haven't tried this method before but my friend has before and normally for this , the ticket number would be way at the back but if you don't mind , then go for it