A K-pop boy band created by Cube Entertainment, BtoB (Born to Beat) debuted in early 2012 and rose to mainstream success over the next few years with chart-topping releases like 2014's Beep Beep EP and the 2015 album Complete. They also made their Japanese debut around this time, hitting number one with the album 24/7. BtoB remained popular during the second half of the decade and rolled out two subgroups, BtoB Blue and BtoB 4U. In 2021, the 4U: Outside EP came out under the BtoB umbrella and featured the group's currently active members. BtoB debuted live on the show M Countdown in March 2012 as a seven-member group consisting of Seo Eun-kwang, Lee Min-hyuk, Lee Chang-sub, Im Hyun-sik, Peniel Shin, Yook Sung-jae, and Jung Il-hoon. A month later, they issued their self-titled Born to Beat debut EP which featured early songs "Insane" and "Imagine." They also starred in their first reality program, Amazon. A succession of EPs appeared over the next two years before BtoB broke through to number one on the South Korean pop charts in 2014. That year, all three of their EPs, Beep Beep, Move, and The Winter's Tale, hit number one, as did their debut album, Complete, a year later. 2016 proved to be another strong year as the band diversified with their first Japanese album, 24/7, formed the subgroup BtoB Blue, featuring members Eun-kwang, Chang-sub, Hyun-sik, and Sung-jae. In 2017, the full group released their second Korean album, Brother Act, which also managed to chart in America on the Billboard U.S. World Albums chart. After 2018's This Is Us EP, BtoB's membership altered when Eun-kwang started his mandatory military service. Min-hyuk took his turn as leader on Hour Moment, then he, too, was called to military duty. By 2020, Hyun-sik and Sung-jae were also serving their military commitments and the remaining members formed another sub-unit, BtoB 4U, which released the 2021 EP 4U: Outside. ~ Timothy Monger, Rovi