[alanX]

I just got the very first chapter of Dragonball, written in Japanese. The majority is Hiragana/Katakana. And just about in every "box" (I don't know what it's called, I'm no comic expert) there is 1 to 2 kanji with furigana.

Not all manga is like this, of course. But just to give you an idea.

So I guess you could use Dragonball for you practice, if you want. Others that use furigana include:

Doraemon
Azumanga Daioh
Claymore
The Melancholy of Haruhi Suzumiya
Any Pokemon manga
inu yasha
meitantei konan (detective conan)
one piece (I've only read this one has furigana, don't know for sure.)
naruto (Same as above)

So all these manga will be written in primarily Kana, and will use furigana whever a Kanji appears.

I hope this helped. Good luck!