M3.

About M3

Music Media-Mix Market, commonly abbreviated as M3, is a semiannual doujinshi convention held in Ōta, Tokyo that primarily caters to doujin music. Both independent and commercial vendors sell various audio and music-related goods, from CDs to musical instruments. It was first held on March 21, 1998 with 53 participating groups, which has since grown to over 1,000 participants per event. It is typically held at Tokyo Ryutsu Center in the spring and fall of each year.