I've just had word back from the Bird Ringing Centre in Moscow that this is a Russian bird. It was ringed in the Chaunskiy district of Chukotka, Russia, on 22 July 2017 and my sighting at Choshi is the first since then. More impressively, Choshi is 4,107 km from where this bird was ringed - quite incredible, and easily my 'furthest' recovery. In London, where we deal mainly in Herring Gull rings, I usually see London-ringed birds, that have just about flown across the breadth of the capital, or, more exotically, birds from Suffolk or Yorkshire. Occasionally there's a more interesting Common, Lesser Black-backed or Great Black-backed from elsewhere in Europe.
To get such a recovery on this Vega perhaps isn't too surprising given where they breed, but I was nevertheless flabbergasted when I opened the email first realised just how far away from Choshi this bird had been ringed!
How far the Vega Gull has travelled - so far that you can see the corners of the earth in this Google Earth screenshot!
Adult Vega Gull 'G4Y' - looking rather worse for wear. Perhaps not much left in the tank for this bird.