Japanese rock band Greeeen do several things to raise eyebrows - the four members are dentistry students and have never made public appearances, not even after releasing six singles and an album. Their faces are covered on photos they post on their blogs. And yet the pop band has become a sensational hit in Japan. Their first album A, Domo. Hajimemasite sold more than 500,000 copies in Japan. Their mysterious identities may be part of what attracts people in the first place. But the actual music accounts for much of the success. The band's icon is a mouthful of teeth with four letter 'e's representing the number of members. The smile reflects Greeeen's sound - uplifting, bouncy and feel-good funky rock. The album kicks off with the extremely catchy Michi. Its piano prelude soon gives way to heart-pounding drumbeats which drive the rest of the album. Ai Uta contains all the elements required of a super-hit - melodic verse, catchy chorus and an emotional bridge. As the album progresses, the tracks become more dynamic, until ending with a soft piano piece. All four members are vocally strong, but it's the music behind the voices that really impresses.