Before the pandemic, direct flights between Italy and Japan departed and arrived at Narita Airport. When I return from Italy or other countries and arrive at Narita Airport, I usually take the train from the airport station.
The train fare from Narita Airport is generally less expensive than bus.
However, sometimes it can be more convenient to take the bus if you have a lot of luggage. The bus takes you directly to a specific destination, such as a hotel in the center of Tokyo. It depends on where you need to go from the airport.