Kra made their major label debut with the single Heart Balance on September 21, 2006.
They band formed in August 2001, and released their first demo tape, Brise, on May 18, 2002. The following November, they signed a contract with PS Company after releasing their second demo tape, Hard Lolita.
Taizo played in ZORO.
It was announced in December 2010 that Mai would be retiring from the music business due to poor health and therefore leaving the band. His last concert with the band would be on December 28 at C.C Lemon Hall.
They have covered four songs from other PS Company bands as '36481?', which is their alter ego band, in an EP called 'Fiction'.