Visual Kei is a fashion NOT a musical genre, any band of any genre can take on this styal and be called as such. However, the majority of bands who dress VK are of the Rock or experimental origin. Visual kei usualy has vibrent colors, feathers, and basically attention drawing features, this however is not true everytime, some VK is more subtle and sence VK is just visual fashion there really isn't a true deffinition. It evovles all the time and differs from band to band and person to person. Just look at all of VK's subgenres, even the subgenres have subgenres. Vk bands tend to be all male, however, if you no where to look you can find female ones to like Exist+Trace.
Visual Kei band/artist inculde Malice Mizer, Girugamesh, Mucc, The GazettE, X Japan (considered by some the father of VK), Miyavi, Gackt, Exist+Trace, Dir en Gray, and so on.