As you are probably aware, the latest version of Microsoft’s Windows Phone OS is Mango, and it appears that Japan’s KDDI will be receiving their first Windows Phone in August and said Windows Phone will actually come with Mango aboard.

According to an article over on WPCentral, by way of Japanese website Nikkei, the new Windows Phone is known as the Toshiba Fujitsu IS12T and will pack a 3.7-inch LCD display and apparently a water resistant housing, but other than that there are no further details on this handset.

Apparently though the Toshiba Fujitsu IS12T has already received clearance from both Bluetooth and the FCC, so it is possible that the smartphone could at some point make its way to the United States, although as Fujitsu doesn’t have a large presence in the USA it is doubtful.

The guys also state that as for being the “first phone with Mango,” they advise caution as apparently the Mango operating system hasn’t yet gone gold and Microsoft has announced any firm release date for the operating system as yet.

Microsoft is looking to drag market share from the iOS and Android platforms with their Windows Phone 7 devices and as you know have partnered Nokia in a bid to assault the mobile space, but still being somewhat in its infancy its unclear whether Windows Phone will actually be able to mount a devastating blow market share wise against Android and Apple.

The Mango update for Windows Phone devices is said to deliver over 500 new features including such things as Twitter integration, turn-by-turn navigation, fast app switching, Windows Live Messenger, and of course if it is destined to play on Japanese Windows Phone devices, language support.

There isn’t really a great deal known about the Mango update for Windows Phone 7 devices at the moment, although it is rumoured the update will be known as Windows Phone 7.5, and that Microsoft has projected Windows for release at some point so it could be we may see is happen in August; more as and when we hear.