MBLAQ, (엠블랙) is a South Korean quintet boy band created by Korean pop R&B singer Rain under his label J.Tune Entertainment. The group debuted in October 9, 2009 at Rain's Legend of Rainism concert. On October 14, 2009 the group released their debut single album, "Just BLAQ", which topped various on-line and off-line music charts in South Korea.
Having trained for two years, MBLAQ was first announced on 21 September 2009, with an appearance on Nylon magazine.The group appeared alongside Rain, in his Legend of Rainism concert. They performed various songs from their produced EP, Just BLAQ and were met with praise. The group released teasers for their debut song, "Oh Yeah" on October 12,with the music video being released two days later. Coinciding with the music video, MBLAQ's debut single album Just BLAQ, was released on the same day, topping various charts in South Korea. The next day, the group made their broadcast debut on M.net's M!Countdown, performing "Oh Yeah".
In early December, the group debuted in Japan, following their performance during Rain's fan meeting- resulting in a documentary being produced surrounding their stay at Japan. Later in the month, the group commenced promotions for their follow up track, "G.o.o.d Luv", with the music video being released December 10 2009. On December 15, it was announced that the group would be part of Season five of the Idol Show (Hangul: 아이돌 군단의 떴다! 그녀 lit. Idol Corps, She Has Arrived!), with the first episode airing a day later.