Welcome. If you cannot find one in Europe then their might be trouble shipping it. You might find one on Japanese auction sites but then getting it shipped will be difficult. https://www.jauce.com/auction/b360498800
Any second hand one you purchase will more than likely have been repaired at sometime, usually with fibreglass and putty, which is fine as long as the tank didn't crack or split. I reckon it would be way more cost effective just to fill it and paint it. Undamaged ones seem to be made of unobtainium. Great looking bike by the way.