Bus is the best way to get to Mt.Fuji for you who will start from Tokyo. Bus is never beaten by any other transportation since it is much easier for foreign visitors, of course cheaper and faster. You can take it from Tokyo’s main train stations and airports just after arriving at Japan.
From Tokyo Station
Destinations: Fuji-Q Highland/Kawaguchiko Station/Mt. Fuji Station
Time: 2–2.5 hrs
Bus departs in from Tokyo Station Yaesu South Exit bus terminal in the morning and from Yaesu North Exit Tekko Building after noon. Long distance bus tickets can be purchased at the bus terminal in Tokyo Station Yaesu South Exit or online via bus company.
From Narita Airport
Destinations: Fuji-Q Highland/Mt. Fuji Station/Kawaguchiko Station
First: 10:35 (Terminal 2)/10:40 (Terminal 1)
Last: 13:35(Terminal2)/13:40 (Terminal 1)
Ticket Counter: https://www.narita-airport.jp/en/access/bus/#section-2
Please note that bus from Narita Airport departs just twice a day.