Sony seems to have outed an unannounced handset by the name of the Xperia Z3+. The handset was mentioned in an accessory compatibility listing.
The White Paper for the Style Cover Window says that the accessory is compatible with both the Xperia Z4 and the Xperia Z3+. Juggly.cn spotted the listing and grabbed a screenshot of the reference before the PDF was pulled.
The Xperia Z3+ could be what the Xperia Z4 is known as outside of Japan. Its dimensions should be comparable, and the addition of the plus sign should indicate that it’s slightly better than the Xperia Z3.
There’s always the chance that the Xperia Z3+ will be a different device altogether. Other possible suspects for the Z4’s international release include the Xperia P2, though it is a different shape and has slightly trimmed specs; and the Xperia Z4 Ultra, although you’d assume that would be a larger device.
The leak doesn’t shed any light as to when we might see this mystery device. But at least there’s some hope that the Xperia Z4 might make the leap across the water even if it is known by another name.