Using Latitude in Japan

I have a Latitude C840 Dell laptop and will be needing to use it to give some presentations in Japan in a couple of weeks.  I know all of Japan has 100V electricity and is 50 Hz in part of the country and 60 Hz in another part of the country.  I will be in both parts.  Will the Dell laptop run on this electricity by itself or do I need to by an electrical converter (110 to 110).  Also what plug in adapters do I need??  Thanks.