I found this drama's title and info! ^_^ EDIT: Well Zemus found it first but I hadn't seen that post lol
http://ja.wikipedia.org/wiki/新・西遊記 aka "New Saiyuki".
It aired from 08 April - 23 September 1994. Ayu appears in episode 11, that's titled along the lines of "Looking to the future" (Google translate calls it "Homeless child to the future" xD)
I found it by searching for the ED song title (100万光年の彼方 - 100million light years away) so if they'd not included the credits we probably never had a chance to find it!