How to enter Japanese characters in UWP(Windows10)

Hi everyone.

We are developing in Japanese Windows10 environment.
With input switching, we can enter Japanese characters and English in most applications.

Well, we are developing an application for UWP(Windows10) with Unity in that environment.

Unity2018.1.2f1
Unity's Platform : Universal Windows Platform
(Build Type : D3D)
Visual Studio 2017
(Windows 10 SDK (10.0.16299.0))
Windows10 : Always accept the latest update

Build a simple scene(There is no script code) with one InputField in Unity and output Visual Studio solution(for UWP).
Then run it in VisualStudio(F5) or run it from package(To install).
Obviously switching to Japanese input on Windows10, but InputField only accepts English(ASCII).
(It assumes a hardware keyboard of Windows10)

We need settings or scripts on Unity?
How can I enter Japanese characters?

thanks

 

We have additional information !

Windows 10 setting:
Input mode notification of Microsoft IME -> Display input mode in center of screen
(In order to clearly check the input mode even outside the task bar)

Remove the focus of the UWP application and set the input mode to Japanese.
However, when returning the focus to UWP application, the input mode returns to ASCII.

Remaining focus leaves Japanese input.
(This seems to be only while the UWP application is focused)

Is this a UWP application specification?
Or is the Unity runtime such an implementation?

Is there a way to control it with scripts?
Or must we create a plugin?

Although we gather information seriously, almost no information can be found on the Web...
Please help !!