There are a number of busses serving Tokyo to and from Narita Airport. If you are staying in Chiba, make sure the bus stops there. Also make sure you know exactly where the bus destination is in Tokyo, (busses go to different locales only) and how far it may be from where you are staying. Usually you can not beat the JR NEX Narita Express train, but busses do give you a free sightseeing experience where as trains are underground when they get into the city. For example I once took a bus into Shinjuku station. The bus dropped us off at the west exit, when in fact we were closer to the east exit of the station, and it was a grueling walk rolling suitcases. The two exits are far apart, so check schedules, length of time to get to your destination and cost.