Every cycle on the 25th day of Month 12, the Oniyans celebrate a festival in honor of the “birth” of Jake Nakagawa, vessel of Xenon Naginata, the Oniyan Emperor, as well as the formation of the Three Warlords of the Oniyan race. On this day, those who celebrate do so almost completely naked (they do wear long cloths to cover their lower torsos) while the Emperor dresses in a different outfit and lets his hair down. This is called the “Black Crystal Festival”, and it shows the collective joyousness of the Corrupted, as well as their twisted sexuality. It is a large festival during which these brainwashed creatures unite and celebrate.

There is a lot of dancing, and the Emperor often gives a speech before the other half of the festivities begin, addressing all of the Oniyans as his “children”. After he puts his crown on, the Emperor showers the Oniyans in his blood as they drink the milk of his sister. Some of them spar in the spirit of the Emperor’s brother, Destiny, but Destiny often refuses to attend the festival. Music is played by musically talented Corrupted beings, adding a twisted yet chipper ambiance to the environment.

The Guardians often perform alongside Oniyan performers; they also make sure that everyone is under the influence of the Emperor’s corruptive yet optimistic and cheerful mentality. There are strange attractions such as Oniyans who can swallow Parasites whole in spirit of the Emperor, some who allow the Aranae models to crawl from their mouths, and much more.

The food, similar to regular Ambrosian food, is drizzled in Parasite blood. Only those over the age of 16 cycles can consume one that is drizzled in Venom unless an accountable parent is present; there have been reports of parents feeding their children Venom.

There are rides for the children, and some of the children actually get to adopt a Parasite to have as a pet. The teens allow a Leviathan to bite them as a “rite of passage” if they wish to go into the Guardian units when they grow up. A lot of fancy jewelry and other material items made of onyx (and sometimes even black crystals) are sold and even given away during this day. At the end of the day, the Oniyan adults (and sometimes the teens) practice the many Oniyan greetings and goodbyes as a sexual means of meeting new people and expressing their love for themselves and their king. During this time, they may or may not get to witness the Emperor designating and creating another Parasite King/Queen before them—but he does honor the ones that already exist. Sometimes he twists the mind and body of a sacrifice—a being of Pure descent.

After the final stretch, Incubus plays a song or sings while someone else plays, and after she is finished, the festival ends with a deep, monstrous “Goln Veli Corruzion” bellowing throughout the crowd.