In no particular order, and for no particular reason for that matter, here are some big portal sites in Japan in case anyone is interested.
A lot of them are properties of the large ISPs.
Will add to this list if other big ones come to mind.
http://www.yahoo.co.jp/
http://www.goo.ne.jp/
http://www.infoseek.co.jp/
http://www.livedoor.com/
http://www.aol.jp/
http://www.excite.co.jp/
http://www.nifty.com/
http://www.biglobe.ne.jp/
http://auone.jp/
http://www.so-net.ne.jp/
http://www.ocn.ne.jp/
