haha LOL Miyavi isn´t jpop...although some of his songs sound like it, he is unique.
well, if you are looking for the visual kei, try the wikipedia. It isn´t very explanatory, but you can get a basic idea.
I really don´t know, why artist in visual rock started to wear make-up, but my guess is, that it has something in common with the name visual- visualy atractive. Visualy catchy. The idea isn´t japanese, it existed in western music as well- f.e. Queen, Kiss etc.
Now, the style changed a lot from it´s begining- the golden era were the 1997- 2002 years. And I guess, they noticed soon, that girls like men, who aren´t hairy, shave their underarms and legs and care for themselves. The make-up is a stage thing, as well as clothes.
And don´t really don´t get offended by answers, that are so passionately defending miyavi, because for us here he is a person Nr.1. Not only because of his looks (which is very attractive), but above all for his music and personality. He is very clever and intelligent and well you can read some of his lyrics, you will understand what I am talking about), he does look feminine, but as I said, he can be masculine.
Now he is in his feminine stage...bu never mind. Just give him a chance...and listen to his music a little...
Well, maybe it is difficult for you as a man (I guess you are a man), but girls like people like him and looks like him. Don´t ask me why. It´s just so. (I bet you have a preferred type of women yourself, but can´t explain always, why..)