Reliable private transfer Narita airport

Can anyone recommend a reliable private transfer service from Narita airport?

The one I see most often recommended on TripAdvisor: https://tokyoairporter.com/

I don't think it is legal, because they don't show their name (of responsible person), phone number, and their address. those are necessary in Japan to make business through internet.
they are unknown persons.

I've never used them, but they have reviews stretching back a decade or more. If they were dodgy, or provided a bad service, they wouldn't still be in business. OP can do their own research, but they certainly don't appear to be the illegal taxi services that regulalrly get shut down.

Personally, I like the train.

I do find this company skeptical. Like Ken says, they don't show their full contact, and nothing in the language of the country they're operating in.

Also, if you set Tripadvisor to English language, you can read some reviews rating them "Terrible" as well. Book at your own risk, and I hope all the money is going to the right people.

Otherwise, the combination of Limousine Bus and taxi after leaving the bus is highly recommended. The buses are right outside, and they'll take care of your luggage all the way through.

I see transport providers at both Narita and Haneda. Most of them are hugely expensive and really do not (in my opinion) provide a good service when a regular taxi is more relaiable. But for larger groups or people that insist on travelling with way too much luggage, then hiring a van can be an option. Not knowing just how far Narita Airport is from the central city and ignorance about how effecient Japanese public transport is are also factors. There are certainly a lot of other companies out there.