So I guess the consensus is that it seems to be a higher end Japanese frame then?
Thanks to all who helped in identifying it.
And thanks for that link, McDave! I've been able to braze for about as long as I can remember, so it should be a pretty simple job.
Unfortunately, it probably won't be staying yellow. It's a really cheap paintjob, and even where it is not flaking off, it looks pretty bad. So it's gonna be stripped and painted right. I'm thinking it'll be a royal blue or purple or somesuch when I'm through with it.
I'll be sure to get some more (better) photos once it's all fixed up. Now to learn all the aspects of bike repair I neglected in my former life!