Hysteric Blue was a Japanese rock band formed in Osaka in 1997. The group consisted of Mayumi Takeda "Tama" on vocals, Takuya Kusunose "Takuya" on drums, and Naoki Akamatsu on guitar. Initially, the band members performed as a four-member group at street concerts near Osaka Castle before being invited to join by Naoki. After releasing two EPs, PICNIC and mf ~Mezzo Forte~, they signed with Sony Records in June 1998. Their debut single "RUSH!" was released on October 31, 1998, followed by their breakthrough hit "Haru～spring～" in January 1999, which reached number 5 on the Oricon charts and became the 27th best-selling single of 1999. Their debut album baby Blue was released on April 1, 1999, reaching number 5 on the Oricon charts and certified double platinum. Hysteric Blue continued to release successful albums including WALLABY (2000), bleu-bleu-bleu (2001), MILESTONE (2002), and their compilation album Historic Blue (2002). They also contributed to various anime soundtracks, including the opening theme for Gakkō no Kaidan. However, on March 4, 2004, Naoki Akamatsu was arrested for sexual assault charges, leading to the band's dissolution.