Gas price in Tokyo fluctuate radically similar to elsewhere.
The price of one liter of gasonline used to be steady at around 100 Yen per liter. As of July 2009, the price of gas in Tokyo is about 120-130 Yen per liter. There are approximately 4 liters to 1 gallon. (1 Gallon of gas = ~$5.00 USD)