Sony has recently announced Xperia Z4 in Japan, but it seems that is not the flagship model that users were expecting. Shortly after the launch, after many users shared their disappointment, the company has revealed that they are working on a new flagship phone.

That could be confirmed by the official document from Sony, which reveal that Sony could rename Xperia Z4 to Xperia Z3+ for the international market. The document called the "Sony SCR30 Style Cover Window case for the Xperia Z4" lists two compatible phones, the Z4 and the unannounced Z3. If Sony decides to launch the new Z3+ and not rebrand it, then the changes could be minimal since the accessory is compatible with both phones.