Buses - how they works

CITY BUSES.
Unlike Kyoto, buses are less used in Tokyo than the subway. During your trip to Japan, you are unlikely to take a city bus in the capital. Bus routes mainly cover those areas of the city that are not reached by subway or train lines.
One of the main companies that runs this service is Toei.
The ticket costs 200 yen in the central area of the city. You pay for the ride when you get off the bus, put coins or use your prepaid card (Suica or Pasmo) in a machine near the driver.
A day pass costs 500 yen.

Compared to the subway, buses are not widely used as a means of public transportation. To move from one city to another in Japan, it is more convenient to travel by subway or train. Buses provide transportation service mainly where there are no train or subway stops. The most popular bus company is Toei. A bus ticket for one ride costs approximately 200 yen. What is special is that you pay for the ticket when you get off the bus, by cash or credit card.

https://www.youtube.com/watch?v=AelyXyY2oVQ