I'm looking to buy some raw Japanese manga to practice my reading with, but they have to have furigana.

Preferably shounen-ai but romance of any kind is fine. I have loveless vol. 1 in Japanese currently and it's got furigana so I assume there should be more out there like it.

I want to buy some manga from Mishima Kazuhiko but I dont think any of them have furigana.

Thank you in advance!

I read Golden Days in Japanese. It's shoujo BL, so it may be what you are looking for. I thought it wasn't too difficult. It has furigana (though there are occasionally words that were written with furigana that didn't match, like it would have someone's name and the kana would read something else. I think this is pretty common for any manga with furigana, I've encountered it in many manga). I have two copies, both the tankoban and bunkobon, and they are both really pretty. The bunko have an extra chapter. I suggest buying the whole series used on Amazon.jp (its sold as a set), because they ship as one item so you can get 3 day shipping pretty cheap. You can also buy the ebooks on bookwalker.jp, but I prefer to paper volumes for reading because it's easier on my eyes.