Hey JLuo,
I also found the same time as JohnBraden but... are you sure about this night bus?!
I know it is one of the cheapest ways to get from Tokyo to Kyoto but... how tall are you guys?
I'm 184cms and had the 'pleasure' once to travel from Nagoya to Tokyo on a bus... it was excruciating.
There was no legroom and a drunk japanese guy snored next to me all the way to Tokyo.
Not trying to scare you... just sharing my experiences!
