Let customer pick currency and language (when entering the store)

[kiwi8]

Hi, right now I plan to use Langify and Vitalis for language & multi-currency.

Ofc i use stripe/shopify payments too.

Imagine I have a German customer, who is traveling in Japan right now, and opens my store. The language will be Japanese and the price in Yen.

That's a bad experience. 

How can I solve this problem?

preferably I want in the top left corner of my store, a flag symbol. if the user clicks on it, he can select the language and currency. Or preferably a popup when entering the store, where customer can choose language/currency, would be nice.

Is that possible? with an app? or custom code? please help me to solve this problem.