I.  Transportation from Narita Airport to
ANA Intercontinental Hotel in Roppongi by Limousine bus (1) and (2) other options:
 
(1) https://www.limousinebus.co.jp/en/platform_searches/index/2/57#timetable

(2)
http://www.rome2rio.com/s/Tokyo-Narita-Airport-NRT/ANA-InterContinental-Tokyo

II.  If you plan to travel within Japan during the reunion, I recommend purchasing a Japan Rail pass which allows multiple rides on any of the JR trains, including the bullet train. If you plan to go to Hiroshima, you can also take the ferry to Miyajima using the rail pass. This pass can only be purchased outside of Japan and it can also be purchased online. Once you purchase the pass, you must have it validated and exchanged for the actual pass in Japan. I suggest you do this at the airport when you arrive, as it takes less time to do at the airport. If you already have the dates and destinations of your travel, you can get your tickets for your trip when you receive your rail pass at the airport. This will save you time by taking care of it when you first arrive.

https://www.japan-rail-pass.com/

III. This site will tell you how to get from one station to another, including the times of the trains.

http://www.jorudan.co.jp/english/norikae/ 


IV. JR Rail Map of Tokyo


https://www.jreast.co.jp/e/downloads/

V. Suica or Pasmo card will allow you to ride any bus, subway or train by simply swiping it when you go through the gate or board the bus. It is reloadable. This is much easier than purchasing tickets each time you take the train. These cards can be purchased at any train station. The site below will explain everything you need to know about these IC cards. These cards come in handy when you are not using your rail pass. 

http://www.japan-guide.com/e/e2359_003.html