Formed by friends at Tokai University in Kanagawa, Japan on February 14, 1992 Penicillin went on to become one of the largest acts in the Japanese Visual Kei scene and is still thriving today, fifteen years later. The band formed with Chisato on Vocals, Gisho on Bass, O-Jiro on drums and both Yuuji and Shaisuke on guitar. Before anything was recorded however the bands line up changed to Hakuei on vocals, Gisho on Guitar, O-jiro on drums and both Shaisuke and Chisato on guitar. This line up stayed for the first single of PENICILLIN SHOCK which was produced by Kiyoshi of then Media Youth. After PENICILLIN SHOCK however, Shaisuke left the band to join Deshabillz.
The band made their major debut in 1996 with Blue Moon on PIONEER LDC. They stayed on Pioneer until 1998 when they changed to east west japan where they were dropped in 2001 and then to omega A.T.music (an indies label) in 2001. Omega happens to be under Omega Project Holdings which Yoshiaki Kondou (Gisho) is the CEO of. However they were only on Omega for a year before being picked up by HiBOOM, which was an indies subsidiary of Avex trax. In 2005 when HiBOOM was closed, they were picked up by Avex TRAX and once again on a major label for the first time since they were dropped from east west. On February 12, 2007 Penicillin celebrated it's 15th Anniversary as a band. On March 9, 2007 Gisho announced that he would leave the band. His last live was his birthday on May 20, 2007 at Shibuya O-East. Since then the band has continued on as a three piece unit.