Earth Coin (Currency)
Earth Coin is a popular blockchain virtual currency before the Outbreak. As this virtual currency is reliable and controllable, it has become the current currency for block trading and financial transactions.
Earth Coin is also the Gacha Currency with which you may draw Character Cards and Weapons from Gacha pools. It can be used to exchange for many other currencies (Crystalas for example) and other precious materials but usually not the other way.
*Blockchain is something that use a network to store information and do auto-correct based upon records stored by the majority of nodes, and hence is believed to be always correct.