Master Key

The Master Key (마스터 키, Maseuteo Ki) is a key to the main door of the Hidden Floor. It allows Regulars to enter directly into the Hidden Floor without having to clear all the tests of the Hell Train. This key was made by the The Workshop.

Several rules govern this "Floor":
 * 1) Revealing details about the Floor causes one to lose both the data they recorded as well as their memories related to it.
 * 2) Only Regulars can enter. (Even the Family Heads are no exception.)
 * 3) One cannot update their data nor bring obtained items or goods out from the Hidden Floor once they have cleared the train.

Using the Master Key to enter the Hidden Floor allows Regulars to ignore the third rule, but prevents them from leaving any record.

Two keys were made by a disciple from the Workshop and they were initially given to Zahard and the Hell Express conductor.