Ugetsu Hakua is an artist who did all of the character designs for the anime Bakuretsu Tenshi / Burst Angel and The Tower of Druaga. Flamboyant is an art book from 2005 featuring primarily Burst Angel artwork but also some of his own original doujinshi illustrations.
A note about this collection. My scan is from 2005 and is very high resolution (average is about 2200x3200). However I noticed that the scan on e-hentai, while lower resolution (about 1278x2000) it had an extra 30 or so pages than my version. Also both versions seemed to have pages slightly out of order. So because I'm a masochist, I just spent the last 3 hours combining the two versions and rearranging and renaming them into what I think is the correct order.