Can you help to identify these frames, bikes or parts?

I saw this road bike with a "shimano super aero" head badge and is apparently Tange 900 tuning and I have absolutely no idea what it is! Shimano Biopace chainrings and "exage sport" groupset. Any clues at all or any tips for identifying mystery frames? Never really had to do it before.

Not sure about the shimano badge - I don't think Shimano made their own bikes, though I've seen plenty of old frames with Shimano stickers, although it may have been a demo bike or something.
Tange 900 is a reasonable clue though - Lugged Tange road frames were not common among European builders and usually indicate Japanese or New World manufacturers e.g. Koga Miyata, Centurion, Shogun, Nishiki, Schwinn, Trek, Ricardo - The kind of bikes we didn't see here in the UK until the MTB boom