Taxi App requires Japanese mobile phone number as contact. The app is fairly bilingual.

Surcharge may or may not apply, depending on taxi company and city. The charge is displayed before you submit the call/booking.

e.g. Tokyo NIHON KOTSU: "extra 410 yen will be charged as pick up fee for each taxi / Booking Fee 0"

There used to be a complete list of all providers national wide on their website, and some were totally surcharge free.

Once you have selected a pick up location, the app prompts you with "arrives in about 5 minutes" in Shinjuku, Tokyo , but not in Suginami (Tokyo suburb), for example.