There is more than one artist with this name: 1) A is a British alternative rock band.
2) A [エース] is a Japanese visual rock band British alternative rock band:
They formed in 1995 in Suffolk, England. The original line up was the three brothers: Jason Perry (Vocals), Adam Perry (Drums) and Giles Perry (Keyboard), with two friends Mark Chapman (Guitar) and Steve Swindon (Bass). Swindon quit the band in 1997 and was replaced by Daniel P. Carter.

Read more about A on Last.fm.