A game item in [[Girls' Frontline]] which permits the player to obtain any five star T-Doll or a player icon*. It is awarded during anniversaries to any player logging in and accepting it, and for completing the final stage of a presently running major event.

In-universe, this item does not exist. It is a white [[eye mask]] with [[orange-tinted eyewear|orange-tinted lenses]].

*While the exchange store for that mask is still open. In other words, a True Core Mask from one event ago will not be exchangeable with anything in the present TCM exchange store. If an event runs parallel to the game anniversary, there will be two TCM exchange stores.
true core mask (girls' frontline)