Firstly, good news is that Hawaii and Taiwan are reporting minimal damage from the tsunami.
The area in Japan which were most badly affected were the Miyagi prefecture area which includes the city Sendai. In 2008 over 1,031,704 people lived in the city, so population at the time of the tsunami is likely to be much higher. Reports are that the city has been “devastated”.
Sendai airport has been totally flooded, and live recordings from military and reporters showed many homes and road traffic being washed away. People in cars were literally trying to out run the waves, unfortunately mostly failing.
Geography of the Sendai Area
Sendai is located at lat. 38°16’05” north, long. 140°52’11” east. The city’s area is 788.09 km², and stretches from the Pacific Ocean to the Ōu Mountains, which are the east and west borders of Miyagi Prefecture. As a result, the city’s geography is quite diverse. Eastern Sendai is a plains area, the center of the city is hilly, and western areas are mountainous. The highest point in the city is Mt. Funagata which stands 1,500 m above sea level. Source: http://en.wikipedia.org/wiki/Sendai