Join Date: Nov 2005
Location: SIN / CNX / SFO
Programs: UA GS, SQ PPS, Hyatt Globalist, Marriott Titanium, Hilton Diamond, Accor Gold
Posts: 1,253
Check out Tower Records or HMV in Shibuya. Both stores are huge (and very crowded) and are sure to have what you're looking for.
Keep in mind that you will likely need to be able to read the kanji for the artist you are looking for or you will be wandering around for a very long time. The CDs are arranged in Japanese alphabetical order (a i u e o ka ki ku ... and so on).