The largest city in Kansai, Osaka has been likened to Tokyo in terms of the population and infrastructure. Especially in central Osaka, the number of people cramming into public transport system could cause a headache for those not familiar with the train routes.
Foreigners on a temporary visa are eligible for the JR Rail Pass or JR Kansai Area Pass (also known as the JR West Rail Pass). These basically allow unlimited rides on JR lines on local or certain limited express trains around Osaka, Kyoto, Nara and Kobe, Wakayama and some other cities for one to four days.
The JR Kansai Area Pass is good for getting to a general area, but may not necessarily get you to the exact location of attractions. For those who do not have the JR Rail Pass and would like to experience more than skimming the surface of Kansai, the Kansai Thru Pass is a 2 or 3-day alternative that provides great value for money. For the same amount as the JR Kansai Area Pass, it covers a denser network, including the subways and city buses of Kyoto, Osaka and Kobe. It may be purchased either online or from the kiosks at convenience stores.
Foreigners on long-term visas who are accompanying a tourist as a guide may also purchase the pass. An additional bit of information for foreigners residing in Japan but not in Kansai, you are also eligible for this pass! My personal experience with the 3-day Kansai Thru Pass exceeded my expectations. At ￥5200, it more than paid for itself on a day trip to Himeji and Kobe on the first day, a day trip to Nara on the second day, and unlimited trains and buses around Kyoto and Osaka as well. Certain spots such as the Osaka Castle are more accessible by bus or on foot than the train, so it certainly does help to have the pass for unlimited rides on hand.
The main station in central Osaka is Osaka station, which the shinkansen also runs through. Osaka Station is also linked to 5 other stations that run different lines: Umeda Station, Hanshin Umeda, Hankyu Umeda, Higashi (East) Umeda and Nishi (West) Umeda. This may sound very confusing at first but the signs in the station are in English and also easy to spot. For specific information on the lines that run through each of these stations, please visit the JP Rail website. Get your train maps out and embrace the hustle and bustle of Osaka!