Hi, it was quite easy. We took Narita Express train from the airport to Tokyo Station (main railway station). From Tokyo station with Yamanote line three stops up to Hamamatchucho station. From there we walked to the hotel, app. 500m. We bought roundtrip ticket, and this was valid until hamamatchucho and also back when leaving tokyo. Webalso loaded Hyperdia Tokyo timtable before the trip on our mobile phones, it was helpful! Have a nice trip! It was amazing city!
I always take the narita express to Tokyo central station, which takes About 50 minutes, from there its easiest to take a taxi to the hotel. Be sure to print the adress for the taxi driver, there are multiple mitsui garden hotels in Tokyo.
I arrived at Haneda - and picked this hotel as it is along the monorail route. The limo bus from Narita airport to Handea airport is probably what I would do. Then take the monorail to Hamamatsucho and walk about 500m to the hotel
Suggest google map, from which you can choose the best way and estimate the time you will get there.