BY-SEXUAL was formed in 1987 in Osaka. They were also the youngest visual kei band to be signed to a major record label, by all of the members only being 19 years old.

An early picture of BY-SEXUAL before they went major.
   Years before BY-SEXUAL was formed, Ryo met Den during his first year of junior high and they quickly became friends. During their time in junior high years, they also met Sho, who transfered from a school in Hyogo. In 1987, the threesome were kicked out of school due to having hair that was too long according to their senior high school's policy. Since they were no longer in school, Ryo decided that the three of them should form a band. Both Ryo and Den already could play intruments, but Sho couldn't and was assigned to be the vocalist.

   While the band was trying to get their act together, Den was a roadie for another Osaka based band, Color. Due to Den's job being a roadie, the band found themselves in Tokyo. One day while at a recording studio, the group met Nao. Nao, unlike the rest of the band, actually did graduated from senior high. Nao joined the band after finding out that they did not have a drummer and named the group, BY-SEXUAL.

BY-SEXUAL were featured in a one-off magazine called R'n'R Graphics, released in January 1990, to promote their upcoming debut single.
   BY-SEXUAL's first concert was April 1st, 1989 with Kamaitachi. Dynamite Tommy, the vocalist of Color, helped the new band out due to none of the members of BY-SEXUAL were in any previous bands. Since both Color and Kamaitachi were bands that record labels wanted, the concert helped BY-SEXUAL out and record labels were soon pursuiting them. By October 1989, the band signed a deal to Pony Canyon. From 1989 to 1995, the band released three demotapes, thirteen singles, eight albums, and a greatest hits album.

   In 1994, the group annouced, via Vicious magazine's November Issue, that Sho was leaving the band. On December 16, Sho officially annouced he was leaving the group in order to pursuit a solo career. In January 1995, Sho left the band. Pony Canyon released a BY-SEXUAL greatest hits album called "Album". This greatest hits album contained two new songs, one with Sho singing and the other one with no vocal track. Some fans have expressed that Sho's sudden departure from the band was why BY-SEXUAL's last album, "Cool", was rushed and didn't felt complete. Some also believe that "Akuyuu", one of the new tracks off of "Album", was a leftover track from the "Cool" recording sessions.

Before the signing of DIR EN GREY, BY-SEXUAL were Free-Will Records most successful band.
   The remaining members kept the band going, even with the lost of their vocalist and record contract. The band went through two name changed. The first was Alzheimer but was later changed to BY-SEX in 1996 due to the fans disapproving of the group changing their name. Ironically, BY-SEX was also the pet name that the devoted BY-SEXUAL fans called the group. Nothing could help keep the band together.

   Nao decided in late 1998 that he wanted out of the group. Nao's last concert with the band was supposed to be in December but a horrible snow storm cancelled the concert. His last concert was postpone to February of 1998. Nao's reason for leaving the band was that it was his time to go and he was holding down the other members' talent. Ryo and Den recruited former L'arc en Ciel drummer, Sakura, to replace Nao. This would be the first step towards Ryo's & Den's next band, Zigzo.

Late Cool era promotions only featured Ryo, Den, and Nao due to Sho having announced he was no longer in the group.
   After Sho's departure from the band, he released one single before retiring from music. Since then, Sho has been a manager. His biggest band being the visual pop rock duo, Feel. Nao went on being the support drummer for Machine and joined Nitro (which later became food.). Nao disappeared from the music scene until 2006, being a member of Nakata band but left the band in 2007. Nao has since been a support member for Machine in 2007 during their Ooh Yeah era. Nao now spends most of his time running a restaurant, but has started food. back up around 2015. Ryo and Den went on being in another popular band, Zigzo. After Zigzo's disbandment in 2002, the two of them went on to form Pt. (pronounced as Platinum) and test-No. Den was also a member of Sister's No Future and AsamixBlackeyes and a support member for Machine in 2007.

   Since BY-SEXUAL's disbandment, the group has reunited twice. The first time in 2011 and the second time for Visual Japan Festival in 2016.