I found Thexder while I was working on updating my Hoot set. I figured I'd share since I didn't see it in any of the "big" sets right now (Neo-Kobe, MAME, TOSEC).
HEREFor the curious, I found it in this collection:
Unrenamed - Japanese Systems I. It's a collection of files identified by the very famous rom datter, Yori Yoshizuki. There are thousands of disks here for various systems. I also found [X1] Makakara in this collection too, which I don't think I could find anywhere else. These sets are great for someone who wants to "dig through the crates" and see if you can find some hidden gems or "new" dumps!