Various cities and transit operators in Japan have historically developed their own individual IC cards, including Suica and PASMO around Tokyo, ICOCA and PiTaPa in Kansai, TOICA and manaca around Nagoya, SUGOCA, Hayakaken, and nimoca in Kyushu, and Kitaca in Hokkaido.
Starting from around year 2013, the system behind all these cards are interlinked, and passengers can use any of these card across any operators supporting any of the above cards.
There are many other systems which have issued their own card but also support these major transit cards now, but those transit cards issued by those systems themselves cannot be used at other systems.
There are still some systems in Japan that have their own transit card but aren't part of this interchanging usage alliance
Note that, while support for this transit cards network have already expanded across entire Japan, there are still different zones, and it is not possible for transit cards to handle movement across zone even if both the entering and exiting station support these transit cards.