Only problem is I'm totally lost with all the confusing titles. SWEET BLACK? Ravex? Golden LUV? who? what? Are these people or something?
Kyats already explained what "Ravex" is, but SWEET BLACK (also known as the SWEET BLACK Girls) is basically a project of sorts that's on the radio and they feature young women as guests, it's trying to promote the image of young, trendy and independent women. Of course Maki is a regular, being a part of the project and all, so when she releases stuff it's under the project's name.
Golden Luv, if I'm not mistaken, is just the name of the song and they just said it featured Goto Maki to state whose singing (same with BoA). I think they tried a different approach with 'titles'.