The network of Osaka Metro includes several cities next to Osaka city. Since Osaka is the second biggest city in Japan, many commuters use it in the morning and after 5 pm. It is crowded at that time. It is very convenient to go around in Osaka city for sightseeing.
Until March 31, 2018, the network was operated by the Osaka Municipal Transportation Bureau in the city government. But the new private operator took over the operations on April 1, 2018. Some special tickets including entry tickets in the facilities are sold at the ticket counter at some Osaka Metro stations.
You can get more information about Osaka Metro through the link below.