Friends since 2000, vocalist Futoshi and bassist OKP-Star formed the Japanese rock band Aqua Timez in 2003. Joining them in the group's lineup were guitarist Daisuke, keyboardist Mayuko, and drummer Tasshi, all of whom made their full-length debut in 2005 with the album Sora Ippai ni Kanaderu Inori. The record reached Number 1 in Japan. One year later, Aqua Timez scored back-to-back Top 10 singles with "Ketsui no Asa ni" (number 4) and "Sen no Yoru o Koete" (number 5), as well as back-to-back album releases with Nanairo no Rakugaki and Kaze o Atsumete. Dareka no Chijōe reached number 2 in 2007, Utai Sarishi Hana hit number 4 in 2009, Carpe Diem hit number 3 in 2011, Because You Are You reached number 5 in 2012, and Asunarou climbed to number 9 in 2016. The band announced its split in 2018 and released The Best of Aqua Timez, a two-disc compilation album featuring hits like "Hachimitsu (Daddy, Daddy)" and "Sekai de Ichiban Chiisana Umi yo." The compilation returned to the charts in 2024, reaching number 70 on the Top 100 Albums Line Music chart. That same year, Aqua Timez reunited in honor of the group's twentieth anniversary, promising new music and new tour dates on the horizon. In December 2025, they came back with the album Umi Ippai Ni Furishikiru Hoshi, featuring the track "Hitoshizuku"
