Concerts in Japan?

Is there a website that lists concerts in Tokyo for Jpop or Jrock? It's not a big deal, but I was wondering if there were any when I am going to be in Japan (the month of May). How would one go about buying tickets for a show?

here's a calender of avex jpop concerts in may. http://www.avexlive.jp/calendar/0705.html

can also check listing at ticket pia which has most events going on. http://t.pia.co.jp/music.html

as for getting tickets from outside japan. there are no official channels for purchase as places like ticket pia only accept credit cards with jp addresses. you would have to go through a purchasing site like http://www.fdjp.com/ or get tickets when you get to japan from ticket pia machine inside a lawson's convenient store, get from scalpers, or ticket agencies.

www, metropolis.co.jp/
has a good gig listing

I am planning 2 week trip to Japan in November and would like to attend big music concert there. Does anyone know where I can look to see if there are any big name bands playing then? I speak only English. Thanks

www.creativeman.co.jp
www.smash-jpn.com
http://metropolis.co.jp/default.asp (in the concerts section on the left).

There are other sites but mostly in Japanese.