2020–2021: Formation and debut, Kingdom: Legendary War. The quartet’s first activity as an unofficial unit was the
Naver Now show
BTOB NOW: Our Concert, which was hosted by
Seo Eun-kwang,
Lee Min-hyuk,
Lee Chang-sub, and
Peniel, and was aired for 3 weeks starting October 27. Throughout the broadcast, the quartet performed numerous songs on 'BtoB Masterpiece One Bar Live' and communicated freely with fans through 'Real-time Q&A'. Their last episode was on November 18. BtoB 4U is a sub-unit of
BtoB, formed four years after
BtoB Blue, and is composed of Seo Eun-kwang, Lee Min-hyuk, Lee Chang-sub, and Peniel. The group was formed due to other BtoB members' military enlistment. The name
BtoB 4U is the name given by Lee Min-hyuk's brother. On ''
Kang Han-na's Volume Up'', Lee stated "It's not my idea. My brother asked me, 'How's the name for you?'." The name contains a double meaning of 'For you' and '4 members united'. It also refers to how there are four members in the unit. Other unit names that were selected after a public survey are BtoB Sky, BtoB Purple, BtoB Black, TeleToB, and SaToB (4 ToB). On November 16, the group debuted with a
moombahton dance genre song "
Show Your Love" that contains a hopeful message to live and love each other even in difficult times. The song was composed by
Im Hyun-sik, composed before his military enlistment. BtoB 4U received their first-ever
music show win on
SBS MTV's
The Show on November 24, 8 days after their debut. On December 2, the group released the official Japanese version of the song. On January 28, 2021, it was officially announced that BtoB 4U would participate in the
Mnet competition series
Kingdom: Legendary War as BtoB, due to the other members serving in the military. ==Philanthropy==