Classical music in Tokyo and Kyoto

I have done some searching online, trying to find info on opera performances, or classical music concerts (chamber music, recitals, or symphony orchestra), that I can go to in Tokyo and Kyoto.
I arrive in Tokyo on Monday 22nd March(yippeee, getting excited!!!) for 8 days and will be in Kyoto from 3rd to 12th April.

I can't find what I think I'm looking for, so would very much appreciate some pointers.

Thank you.

This list may help you.
http://www.japantimes.co.jp/entertainment/advanced_booking.html
Also, there's a free lunchtime(organ & violin) concert at Tokyo Metropolitan Art Space (Tokyo Geijutsu Gekijo in Japanese) in Ikebukuro on March 25.
http://www.geigeki.jp/saiji_002.html
(Click on the poster and you'll see some info in English)

thanks a million for this, wow, I might need to stay longer!

J