The Secret Base (秘密基地) was a secret headquarters used by the Inner Senshi in Codename: Sailor V, the Sailor Moon manga, the live-action series, and Sailor Moon Crystal. It did not appear in the original anime, though it may have been partially responsible for inspiring the Game Machine.
Sailor Moon Manga and Crystal
In the manga, the Secret Base was located underneath Game Center Crown and was entered through the Sailor V game there. It contained many large computers, which were mainly used by Sailor Mercury, Artemis, and Luna. Evil Prince Endymion managed to breach the headquarters with the help of a brainwashed Motoki; it was here that he severely injured Luna, which made Usagi realize that he was not the same man he once was.
The Secret Base was damaged in a explosion that occurred due to the fight with the Dark Kingdom, and lead to Motoki (after recovering from the effects of being brainwashed) discovering the identities of the Sailor Senshi. The Base was not seen again after the Black Moon arc of the manga.
Pretty Guardian Sailor Moon
|The Secret Base in PGSM|
In the live-action series, the Secret Base was located underneath Karaoke Crown, Game Center Crown's live action counterpart, possibly in another dimension. The Senshi were given the Karaoke Crown Passports by Luna so they did not have to pay to gain access to it. The door leading down to the base would magically appear when a Senshi willed it.
This version of the Secret Base had a much more homey feel than its manga counterpart. When it first appeared in the second episode, the decor was mostly white and bare, though it had some fun things for the Senshi such as a stage with a karaoke machine and large candy dispensers. As time went by more items appeared, including colorful decorations, a large couch, and photographs of the Senshi on the walls. In the center of the room stood a table that started out white, but after a few episodes became yellow with a round blue placemat to one side, making it look like a crescent moon. It was surrounded by five chairs: a pink one for Usagi, a blue one for Ami, a purple one for Rei, a green one for Makoto, and an additional chair intended for Minako, which started out white and later turned orange.
The Secret Base was not seen again after the events of the Final Act.