Overview
BR-001, also known as the Endless Carnival, was the first Black Ring to appear outside of the Perishing Star impact crater. It was also responsible for the existence of Sinners becoming public knowledge, as Hamel was dubbed the "first publicly known Sinner" after her role in its descent. For years, it was believed that Hamel was the originator of the Ring, but in actuality, it was begun by a wandering Corpus acting of its own accord. The Black Ring appeared in N.F. 089, interrupting the grand reopening of the DisCity Carnival, and lasted for 23 years before it was eliminated. The FAC established a perimeter of contamination shields thirty to fifty meters from the Black Ring, but its long existence is nevertheless responsible for the contamination of the Rust. The logic of the spiritual world of the Ring was created by the Corpus's twisted desire for love.
More than 30,000 people disappeared during the Black Ring's initial descent, with an additional 200 or more people being lost to the Ring each year since.
Descent
On N.F. 089.06.25, the DisCity Carnival reopened for the first time since the DisSea Explosion five years prior. The Carnival was meant to be a celebration of the City's recovery, but on the third day, June 27, a Mania crisis broke out in the Carnival. At the time, it was not known that the DisSea Explosion was anything other than a one-off event. The official record showed Hamel entering the Carnival at 12:39. At 13:10, an S-Level Sinner reaction was detected, and BR-001 erupted over the Carnival. As such, Hamel was assumed for many years to have been the originator of the Black Ring. In truth, Hamel was not responsible: a wandering Corpus, previously undetected even by Parma, had come to the Carnival instinctively seeking companionship and catalyzed the Black Ring by feeding on the Mania of the many thousands of people in the Carnival. Hamel did not enter the Carnival until the Mania crisis was already underway. She had followed her brother, Norman, who was drawn to the Carnival because it promised to ease the stress that he suffered as a result of caring for Hamel.
When the Black Ring descended, Hamel used her ability to create an illusory world that overlaid the entire Carnival. Her goals in this were twofold: firstly, the illusory realm rejected humans, keeping Norman and any other uncorrupted individuals from entering the Black Ring. Secondly, it eased the suffering of the Corruptors who were trapped inside, which Hamel had wished to do ever since she became a Sinner. The Corpus, envious of the adoration that the Ring's occupants showed toward Hamel, began to impersonate her and her dance.
Existence
Over the next 23 years, BR-001 remained mostly dormant, but erupted several times, eventually forcing the FAC to abandon the Rust altogether. (7-1) Corruptors are drawn to the remnants of the Carnival, and the sounds of their laughter and wailing can be heard even from outside the Black Ring. Although the Carnival welcomes Corruptors, it rejects humans, with its occupants pushing out any humans who stumble into it -- although not attacking them unless provoked.
Inside the Black Ring, the dilapidated Carnival attractions became tangled with hellish tentacles of contamination, but Hamel's illusory world masked the horror of the environment. To the Ring's occupants, the DisCity Carnival constantly relived its last day, hiding even the Black Ring itself not visible in the sky, and the Corruptors who occupied it were disguised as park mascots. Corruptors flocked to Hamel, as her dance eased their suffering. The Corpus was also kept dormant, constantly being put back to sleep and stopped from emerging from the Ring. (7-10) In both forms, the spiritual realm of the Ring displays the same powers: deep-level mental interference allowing access to its occupants' memories and the ability to create illusions of their mental images to exploit their emotions.
Hamel's ability single-handedly kept the entire Black Ring under control for more than two decades. Although she could have maintained this balance indefinitely, outside forces sought to disrupt the equilibrium inside the Ring. The Underground worked for years to penetrate Hamel's illusory realm and funnel contamination through xenobodies into the Carnival, feeding the power of the Corpus until it eventually would have been able to overwhelm Hamel and seize control of the Ring's spiritual realm.
Elimination and Aftermath
After the brief appearance of BR-004, the Chief of the MBCC was arrested by the FAC and held on suspicion of their involvement in the Black Ring. In order to prove their innocence, they convinced Langley to allow them to eliminate one of the other Black Rings that still existed in DisCity. The Chief, along with Hella and Hecate, penetrated the illusory world of BR-001 and convinced Hamel to end the illusion so that they could confront the Corpus directly.
When the illusory world was dispelled, BR-001 broke the FAC's containment and cases of mental abnormalities spiked in both Syndicate and Eastside, with the affected parties all moving towards the Rust. When BR-001 was subsequently eliminated, the FAC surrounded the entire Rust with troops, anticipating the tens of thousands of Corruptors who had been lost to the Ring over the years to stream out and attack the surrounding districts. However, not a single Corruptor was found nor a single casualty suffered, as Hamel's dance continued to keep those who had suffered in the Black Ring under control. With the ring destroyed, the remains of the amusement facilities were to be removed from the site of the Carnival by the FAC to eradicate any risk of spreading Mania.