SYNK is the state of connection between a human and an avatar. According to Karina and æ-KARINA, a SYNK occurs when an avatar can send a message to their human counterpart. The more people share their thoughts and feelings, the higher the SYNK level is. When the SYNK level is at its peak, an avatar can REKALL, that is, materialize itself into the real world.
When the connection is forcibly cut short, it is called "SYNK OUT".
Both avatars and humans can synchronize and merge, enabling to feel each other's senses, activate their own abilities, and cross dimensions. This is known as "SYNK DIVE". Procedures for accomplishing the "SYNK DIVE" phenomenon are unknown and unbeknownst to the members, except for NAVIS.