Orochi

About
Orochi is the legendary serpent that is sealed within Miko Institute, and is also the foundation of JAPAN. It said that every huge earthquake that occurs in every hundred years is caused by Orochi's shedding. In order to suppress the scope of earthquake, Miko Institute performs a purification service to gather negative emotion from human males through sexual intercourse.

Originally, Orochi supported the landmass that forms Japan, which was only split off from the mainland after Orochi went on a rampage in NC0321. After the Tenma Bridge was built, Orochi's support is no longer necessary. It went into sleep but caused massive earthquakes once in a while when it shredded its skin.

Orochi is heavily based from the legendary 8-headed and 8-tailed dragon in Japan, Yamata no Orochi.

Sengoku Rance


Orochi first mentioned by Natori during her conversation with her followers. Miko Institute is known for performing a purification service which includes a sexual intercourse between its miko and a human male who won the random drawing. This, is actually part of the ritual to calm Orochi's activities. Every miko who bears the human male's emotion shall be sacrificed for the ritual to succeed.

Many people have tried to defeat Orochi before, though each and every one of them died during the process.

Soon after knowing the fact (especially the part with miko and sacrificial), Rance decides to defeat Orochi once and for all with all of Oda army assembled in its Dungeon. On the last floor, it's revealed that Tamagushi Fuuka, is actually an Orochikko/Orochi Lady. Having all of her memory restored, she begs for Rance to defeat Orochi. With that, all of the Orochikko's soul, including hers, will be able to move to afterlife, so they can at last rest in peace.

Orochi was defeated in the canonical storyline of the Rance games.

Kichikuou Rance
In the non-canonical Kichikuou Rance, Orochi performs a somewhat similar role. After Rance learned that the miko Fuuka is to be sacrificed to Orochi as a part of the ritual, he could decide to whether face off against Orochi and save Fuuka. Different from Sengoku Rance, Fuuka would go on to live a normal life if Orochi is defeated.

Abilities
As expected from a holy beast of his size, Orochi was an immensely powerful being.