A Cluster (クラスター, kura sutā) is a unit of many Ex-Machina. Due to the fact that Ymirein is the former leader of Cluster E, there seems to be an abundance of clusters. Ultimately, all clusters follow their call-sign Einithi. A cluster is able to forcefully excommunicate a unit from the rest of the cluster. This can be due to many reasons such as the unit experiencing failure such as when Schwi wanted to know what a heart was. However also in Schwi's case, if for good reason the unit wishes to reconnect with the rest of the race, it would take 251 seconds to do so. During this, damage to the unit is unacceptable.
Also called "The Collective" when spoken to, it acts as a hive mind able to alter any Ex-Machina to whatever it sees fit. Its ultimate goal is to become a collective of information in order to advance themselves even further.