Multibyte Language Search?

Hi,

I’m developing a site for a Japanese customer who requires that searches are able to be done in Japanese.
I can enter Japanese text and search successfully on my iMac, but received a complaint from the customer that when they enter text into the quick search field from their iPhone, the text is automatically converted into roman letters. I tested and found that this is the case on both iPhone and iPad.

Can someone tell me what the issue might be here?

Cheers,

Eric