How can I change a font-family of Primary Menu?

If you want to change a font-family of Primary Menu, you can add the following code to the style.css file:

.navbar .nav li a  { font-family: ....; }

Note: you can find the font here: https://www.google.com/fonts
Also, please take a look at the following topic to find the answer:
http://cmspioneer.com/designwall/question/how-to-change-fonts-and-font-color/
Hope this helps !

Thank you for your answer.
But it doesn’t work since the font I want to use (Japanese) is not included in google fonts.
I’m wondering if I can override the font setting by deleting the existing one.
Do you know how to do it?