The Basilicom is a holy organization in the series that serves directly under the CPUs of each nation and governs each land. Each nation has their own Basilicom and serve as both a place of worship for the people and a place where they can be granted an audience to meet them in person.
Basilicoms are holy organizations run by those who serve the goddesses. Long ago, Basilicoms were created by CPUs, Console Patron Units who are also called goddesses. The Basilicom staff assists them in governing the world. On the other hand, they preform missionary work to spread their beliefs. There are two parts to a Basilicom: the sanctuary where the goddesses are cared for, and the parliament for political activities. The Basilicom also manages the sky harbors, requiring people to obtain permits to travel to different land. They also preform research regarding the monsters in Gamindustri.
In Hyperdimension Neptunia there are two parts of a Basilicom: The Parliament and the Sanctuary.
This is the branch of the Basilicom that cares for their goddess of worship when they descend from Celestia to visit the human world. Aside from pampering their goddesses, some of the members act as evangelists to spread their beliefs of their individual goddesses across both their land and other lands.
This is the Branch of the Basilicom that handles political affairs and are seemingly in control of the landmass when their goddess is not present to take control of the direction the landmass takes. Basilicom Parliaments also handle Terraportation and the research of the uprising of monsters in their respective landmasses. The Parliament does not have complete control over the nation and works somewhat as democracy, only being able to create changes into the respective landmass with a significant number of votes.
In Hyperdimension Neptunia mk2 and onward, the Basilicom's play a different role in the series, acting as the homes and workplaces of the CPUs while still serving as a holy organization at the same time. Just like in the original Hyperdimension Neptunia, people can request audiences with the goddess here.
Each Basilicom generally has its own unique style and structure and is often a visual landmark in the capital city of the nation due to its unique design and large size. This is unlike Hyperdimension Neptunia where all the Basilicoms looked more or less the same.
The goddess of the nation plays a more active role in the growth of their nations and the branches of the Basilicom that were present in the first Hyperdimension Neptunia are seemingly non-existent. The CPU of each nation does a vast majority of the work such as paperwork, public relations, and completing quests.
In addition to this, Basilicoms also have Oracles who act as the secretary of state for the nation. The oracles also have their own duties when it comes to helping the goddess manage the nation and also managing the Basilicom. One of their main duties is being in charge of the Guild and managing the quests that go in and out.
In the Ultra Dimension the Basilicom is seemingly structured the same way as the Basilicom in the Hyper Dimension. However a major difference is the lack of Oracles, which are present in each nation in the Hyper Dimension. It is possible that the CPUs in the Ultra Dimension do all the work, but is not likely due to presence of individuals like Histoire and Mr. Badd.
Histoire is inferred to manage the Basilicom, however whether or not she manages the Guild like in the Oracles of the Hyper Dimension is unknown. Additionally, Lowee is shown to have a Prime Minister, formally being Mr. Badd. The Prime Ministers job is akin to that of the Parliament from the first Hyperdimension Neptunia game. It is possible that Basilicom structure in the Ultra Dimension is a combination between that of both Hyperdimension Neptunia and Hyperdimension Neptunia mk2.
- Basilicom is a term used only in the English version of the series. In the original Japanese version of the game the term "Kyoukai" meaning "Church" is used.