業 / 蒼い月 is a single-sided cassette tape and the first release by Dir En Grey. It was recorded at M4 Studios in Osaka, Japan, approximately in March 1997. The tape was sent to various radio stations and people in the music industry and as such, it can be heard during an interview on May 30, 1997, when Kaoru appeared on the radio show PowerRockRevolution. You can listen to the interview here. The two songs were also used on 1997.6.14 目黒鹿鳴館 and 1997.6.27 COWBOY WORLD, respectively.
Being the first musical output by the band, this demo tape is highly sought after and was sold for prices as high as ¥48,600.