Probleme with japanese search

[Paka76]

Hello,
I hope someone can help me. I indexed a japanse website. In the search field I add a Japanese word (は、現在8か国にそ ), but on my result page i get no hits.

After that I searched for an english word and I get hits. How can I search for Japanese words? I add a attachment from my result page.

In the config file I activated ENABLE_JPKANA.

Enclosed a cutout from my config file:
define('PHPDIG_ENCODING','utf-8');
define('DETECT_ORDER','UTF-8,KOI8-R,JIS,SJIS,CP936,BIG-5,EUC-CN,EUC-TW,EUC-KR,EUC-JP');
define('ENABLE_JPKANA',true);
define('CONVERT_JPKANA','KVa');

Thanks for your help.
Greetings Paka76