I have just tried Text Recognition Sample in Unity.
It is really really wonderful.
My question is that is it possible to replace the English word list by a new language word list, say Japanese one?
I have tried to add some Japanese words to Additional Word File as well as Additional Words in Inspector of Unity, but the sample does not recognize those Japanese words.

If I may add, for Text Reco, feel free to consult this page of our developer guide:
https://developer.vuforia.com/resources/dev-guide/word-targets
which explains what is currently possible and what is not;
in particular, the Section titled "Supported characters" explains which characters are supported;
as you can see, characters that belong to non-European alphabets, like Japanese, Korean, Chinese, are simply not supported.