The USA part was 48th Street custom guitars. Most were shipped there as they were the main dealer at the time and then as posted above, they did some assembly there as well.
IMO these were the best ESP's every made. I had two Horizons from 48th street, one being a factory second where the binding had prematurely aged, and according to them was to go to one of the guys in Queensryche but the binding was jacked. They had tucked it in a case and were sending it back to Japan when I bought it site unseen. Best guitar I ever owned.
The original runs of Horizons, Mirage Customs, Mirage Deluxes, Eclipses's, M1's...all with the Jackson Lawsuit headstock were straight up incredible guitars.
To @Neoclassical.Sucubus you won't find a better made ESP than that in my opinion. However take note, that guitar has the original ESP Sinclair Floyd Rose on it. "If" all the parts are still intact it's IMO the best Floyd Rose ever made. It's smaller, more compact, top locking and much easier on the palm of your hand...really just a fantastic version of a Floyd. The issue is it uses little plates to sit on top of the string when locking down...at least that's the best I could describe it. Lose those plates and it can be an issue locking the string down. I remember first time taking one to my tech and was dude, you cannot lose these. Regardless it's still my favorite version of a Floyd.