Japan has distinguish 4 seasons, including very hot and humid summer and cold winter.
Although frequency of trains in Tokyo metropolitan area is relatively high, waiting the next train can be a pain when you are in summer or a in winter.
Therefore a lot stations in Tokyo metropolitan area are now equipped with waiting rooms at the platforms. The waiting rooms are very simply building but usually equipped with air conditioners.
Then, the doors are either manual or automatic doors. In case of automatic doors, usually you have to push the buttons on the doors to open it.
By the way, there are now common to have waiting rooms at the platforms but most of the stations do not have any waiting area or lounge inside the main station buildings except for passengers of Shinkansen. It is very interesting that JR do not offer any lounge for their Green cars(1st class) passengers at all. Then, there is no discount for frequent users except Zipang Club which is for seniors.