Greeeen (stylized as GReeeeN) is a Japanese pop rock/hip hop/breakbeat vocal group from Kōriyama in Fukushima Prefecture, comprising the all-male four members: HIDE, navi, 92 (read as "kuni"), and SOH.
They made their debut with Universal Music in 2007. Their logo image is of a mouthful of teeth, and the four "e" indicate the number of members and the dentition that you can see when you smile because of all of them were graduated from the Faculty of Dentistry. The sound production is handled by HIDE's older brother JIN, a former guitarist of Pay money To my Pain. According to their website at Universal Music Japan, their catch phrase is "Rock 'n' Breakbeats with four microphones".
One notable characteristic is that none of the members have ever shown their faces in the public sphere as a part of GReeeeN, whether in their promotional videos, CDs, television performances, or the Internet. In their only performance on TV-U Fukushima's music show Music Bar Palo Palo (broadcast on January 19, 2007), the group even went as far as censoring their faces during the performance. The members' identities are still unknown, as their faces have never been made public. At first, the group stated that they would wait until all of the members passed the 2009 dental license exam before revealing their faces, but later in late 2009, they indicated that they will still keep their identities secret to avoid any interference with their careers as dentists.
All members studied at the dentistry department at Ohu University in Koriyama City, (Fukushima Prefecture) and the group debuted while still in school in 2007. In 2010, all members get a dental license and work as dentist in Kōriyama. In 2019, they were named as 'Frontier Ambassadors' for Kōriyama city. In 2013, GReeeeN was announced in the text on the CD that HIDE and navi will travel to Hokkaido. 92 will travel to Okinawa and SOH is still working in Kōriyama.