Being someone who plans to come out as a rapper on youtube, I decided to look at the underground game even more, I must say, it's way more positive than the mainstream. Here are some sick Hip-Hop/Rap producers and artists that are legendary!

Tokyo Kid
This guy really not well known at all! with only 100+ subscribers, this dude needs attention! Oh and he can rap in Japanese:
http://www.youtube.com/watch?v=nF4JmmRaVyk

Immortal Technique
This dude is a real legend! I've always looked up to him and he is definitely one of my favourite rappers of all time!
http://www.youtube.com/watch?v=qggxTtnKTMo&list=AL94UKMTqg-9DcY-U_YuQ5iD0ahZ8wKmT-

Lowkey
This guy isn't really underground but he definitely shook the underground with his words! He has been arrested and sent to jail without trial, had his home raided and banned from London just for rapping, he has now retired at 24, continuing his studies.
http://www.youtube.com/watch?v=ISGeYafLSXg&list=AL94UKMTqg-9CJP4W8d_d-Sl6wxxRPgxri

Natsu Fuji
This producer is top notch! From K-Pop to Hip-Hop to Trap, this dude does it all!
http://www.youtube.com/watch?v=4b0mzFdiuq4

Killing Spree
Long story short, he does hip-hop remixes of anime openings and endings.
http://www.youtube.com/watch?v=LY_2VkLeJg8

D-Pryde
He's caught Canada in the palm of his hands and crushed with his fresh style. He has been praised for his originality (not as much as he used to) and I look up to him as another teenager rapper.
http://www.youtube.com/watch?v=Tan6MJTNS0E

Well, here are some of the million underground cats today, I hope to get as big as them and not any bigger (due to my own personal reasons), enjoy the hip-hop! Remember, it's not just a genre, it's a movement to promote peace, love, unity and having fun!