Only Facebook SDK 'name' kanji can be retrieved

let graphRequest=FBSDKGraphRequest (graphPath: "me", parameters: ["fields": "id, name, first_name, last_name, picture.type(large), email, locale")

As you can see above, I have retrieved profile-related data from Facebook.
You can only get 'name', 'first_name', or 'last_name' data in Chinese characters.
Is there a way to get it in romaji?

If I had a Facebook account called Taro Yamada, I would like to retrieve data like Taro Yamada.

It seems to specify 'locale', but I don't know how to describe it in Swift.
It may be unavoidable, but please help me...

2016.1.23 Additional information

let graphRequest=FBSDKGraphRequest (graphPath: "me", parameters: ["locale": "en_US, "fields": "id, name, first_name, last_name, picture.type(large), email, locale")

Specifying parameters as shown in did not change the result.
Maybe I don't specify locale by code, but I set it up on Facebook's app management page.
We are looking for answers!