seat cluster looks very much like a version used on some ALAN Carbonio frames, but the fork seems to be not original (steel?)
there was also a Japanese-made frame sold by Performance that has some similarities, but also several important differences. Like the stays and seat cluster. Not sure if the maker of those was ever discovered, but speculation was it was NOT SR/Litage because of too many differences. Same frames may have been badged as a "DuralAll" as well as Panasonic and possibly came with AL-alloy tubes as well as CF or blend of CF and Kevlar fibers

EDIT, that mystery Japanese frame may be made by Nakagawa, but this ebay ad shows it also has major differences to the OP's:
https://www.ebay.com/itm/226171373304