You start with it silly! You get it right after you fuse with Omega-xis for the first time. On the other hand, you might be referring to the BN Mega Buster, and if that is the case please state it in a separate question.
After Megaman NT Warrior came Mega Man Star Force.
Viz Media has just announced that the Mega Man Star Force anime is up for streaming on Hulu and Neon Alley.
Mega Man Star Force happened in 2006.
MegaMan Star Force - 2007 TV was released on: USA: 25 August 2007
Mega Man Star Force was created on 2006-12-14.
December 14, 2006
yes
Yes.
MegaMan Star Force - 2007 Alien Attack 1-10 was released on: USA: June 2007
MEGAMAN STARFORCE 2 IS COMING MAYBE IN FEBUARY
http://www.gamefaqs.com/ds/935703-mega-man-star-force-dragon/faqs/49832 go to that link and scroll to somewhere around the middle to find it... its kinda confusing
you cant