THE DEVIL INSIDE is a visual kei solo project based in Tokyo. The project, active since June 2021, is led by vocalist ARYU (阿龍), who was previously a member of the band ＭＯＲＲＩＧＡＮ and is currently in Tokyo INFERNO (東京インフェルノ). The project features a rotating lineup of support musicians, including guitarists YUIHA (唯依葉) from Tokyo INFERNO, Daren from NOKUTO, and PITTY from ＭＯＲＲＩＧＡＮ. Bassists NATSUKI (夏朧) from ＳＨＩＶＡ and Ximakun from M.A.D. also contribute, along with support drummer Hiroshi (鴻志) from DIMLIM. Former support includes bassist hayato from KNOW MEN.

THE DEVIL INSIDE was officially formed on June 6, 2021. The project released its debut digital single "AGEHA" on January 24, 2023. Their first live performance took place on June 6, 2023, at Shibuya REX, which coincided with the release of their second digital single "IN THIS WORLD." Later in the year, they performed at Ikebukuro BlackHole on November 16, 2023.

In early 2024, they continued to release new music, with the digital single "BEAUTIFUL NIGHTMARE" coming out on February 11. The project marked another milestone with a sponsored live event titled "SIXSIXSIX" on June 6, 2024, held at Shibuya REX, featuring ARYU alongside musicians YUIHA, Daren, NATSUKI, and Hiroshi. Read more on Last.fm. User-contributed text is available under the Creative Commons By-SA License; additional terms may apply.