Osaka Underground (大阪アンダーグラウンド) is a mini album from out of survice that will be released for the VOC@LOID M@STER 30 event. The album contains 6 tracks featuring IA, Hatsune Miku, and GUMI. Track 6 is an instrumental version of the first track. The front and back of the album cover are reversible. A crossfade of the album can be heard on Nicovideo and YouTube.