Here's something I picked up lately, bike came with a very eclectic mix of parts including a few nice things that were worth the asking price, wondering if anyone here can suggest an identity for this very basic frame. Maybe someone will recognize the lugs.

Paint is a mystery, at first I thought it was a basic DIY job because it's very rough (if it wasn't for the fade I'd think it was brushed-on housepaint) and there's no sign of any decals. But... there's a serial number visible, so maybe the paint is original.

Specs:
Probably hi-ten steel to judge from the weight
Takes 25.8 seatpost
Japanese threaded headset and bottom bracket
Fork with decent chrome
120mm rear spacing

Pictures: