Codespace is a plane of reality above and beyond that of T.O.E.'s normal world. It is a place of endless stars where supernatural beings can commune with one another, or guests they've dragged along, in unearthly forms. Some beings are even capable of existing in codespace in their normal forms, though whether this distinction is voluntary or not is unknown. Codespace appears to take over the world of T.O.E. during the weekend.
Rats appear to have a strong connection to codespace. Iko has also demonstrated the ability to both travel into and traverse codespace.