biber tries to treat CJK in .bib as ASCII, despite the file being saved in Unicode -> error in biblatex-chicago references

Question

I'm trying to use a .bib that contains CJK characters for my document which uses biblatex-chicago and biber. However, biber writes out the bibliography in ascii when I run

biber <filename>.bcf

This prevents pdflatex to process the bibliography properly, and the references are garbled. My document is:

\documentclass{article}
\usepackage[american]{babel}
\usepackage[babel]{csquotes}
\usepackage[notes,isbn=false,backend=biber,bibencoding=utf8]{biblatex-chicago}  
\addbibresource{try.bib}
\begin{document}

Test\autocite{Xunisha2012}

\end{document}

and my .bib is:

@book{Xunisha2012,
Author = {{Xu Nisha}},
nameaddon = {徐倪莎},
Publisher = {Payot},
Title = {Yi jiu qi qi nianjie de gaokao},
titleaddon = {一九七七年届的高考},
usere = {The 1977 session of the university entry examinations},
Year = {2013}}

Thank you for your help!

Update

When I run biber with unicode:

biber -u -U try.bcf

I get nothing in the CJK fields instead of the garbled text from before; still no CJK output.

Answer 1

Thanks to Leo Liu's comment, the problem is now solved. When I write my file like this:

\documentclass{article}

\usepackage[fallback]{xeCJK}
\setmainfont{Gentium Plus}
\setCJKmainfont{SimSun}
\setCJKfallbackfamilyfont{\CJKrmdefault}{NanumMyeongjo}

%\usepackage[american]{babel}
\usepackage{csquotes}
\usepackage[notes,isbn=false,backend=biber,bibencoding=utf8]{biblatex-chicago}  
\addbibresource{try.bib}

\begin{document}

中國중국ちゅうごく
Test\autocite{Xunisha2012}

\end{document}

And run

xelatex

it works.