Kageyama Hironobu... i've finally remembered :P, that's the name of teh JAM project guy... the one that had sung/written a ton of anime songs ^^
http://www.jamproject-fan.com/jamproject/member/kageyama.html i hope they release the song as a single or something soon...
as for the ending theme, its actually sung by one of the cast 京本政樹, the shrink ^^ hmmm... and he seems to be an interesting artist that's done a whole heap of drama/tokusatsu... yup, go ignorant me go... xddd
http://www.la-cetzna.com and while i'm searching around the net i found this clip of ibu shinji aka garo aka konishi hiroki... it's old, but hey i've never seen it before :P, and it's nice to see konishi smile so much (as oppose to the constant brooding of shinji and garo) x___x
http://www.mmv.co.jp/products/report/031104/02.html