The J-pop duo ClariS was formed by teenage singers Clara and Alice in 2009, while both members were junior high school students in Hokkaido. Disguising their real names as well as their physical appearances, the two singers began uploading their own versions of popular songs later that year, then released their first original track, "Irony," in October 2010. Used as the opening theme to the anime series Oreimo, "Irony" became a Top 10 synthpop hit, reaching Number 7 on Japan's Oricon Weekly Singles chart. A second single, the platinum-selling "Connect," followed in early 2011 and continued the band's momentum by peaking at Number 5. "Nexus" returned ClariS to Number 5 later that year, with "Naisho no Hanashi" reaching Number 2 in 2012. All three songs appeared on the group's gold-certified debut album, Birthday, which peaked at Number 2 upon its release in April 2012. Second Story was released in 2013 and climbed to Number 6, with 2014's Party Time becoming the group's second album to reach Number 2. Alice left the lineup in 2014 to devote more time to her schoolwork, with Clara welcoming a new member, Karen, into the group. This new incarnation of ClariS released a new album, Fairy Castle, in 2017, earning four Top 40 singles along the way. The related Fairy Party followed in 2018, charted at Number 8, and produced two Top 10 hits, including the gold-certified "Hitorigoto." Following a pair of compilation albums celebrated the duo's tenth anniversary, ClariS remained in the Top 10 with 2022's Parfaitone, whose tracks included the Number 8 hit "Careless."