I seem to remember another anime themed indie SHMUP from the early 2000's that sounds very similar (and isn't Starscape, although you should buy it cheap on Steam, it's really good). It may have appeared on HOTU, but I don't recall the name. I believe it was released as freeware at the time.
I'll be looking around. Trying lists like these first:
http://indygamer.blogspot.com/search/label/shmup2006
Edit: The game I'm thinking of is
Idinaloq,
(Dev site). Probably not what you're thinking of, though. It's 3d.