This record contains the KPRE-15 stage of Yuuki Theory / Yuuki Collapse Theory, named the Ouroboros System. The document presents a cyclic closure candidate connecting black-hole internal bipolarization, expansion through an old interference field, pre-Higgs-range CMB as an 18-tensor effective projection, Higgs-range particle generation as 27-tensor closure, the present approximate or parallel-candidate universe, and a future Class 3 black hole as a possible recontraction nucleus. The central structural distinction is: - CMB stage: 2 layers × 3 states × 3 boundaries = 18 tensor effective projection. - Particle stage: 3 layers × 3 states × 3 boundaries = 27 tensor closure. - Difference: ΔN = 27 − 18 = 9, interpreted as the Layer-3 closure block. - Class 3 black holes are treated as candidate recontraction nuclei for a future cycle. This work is a conceptual and theoretical research artifact. It defines a cyclic closure candidate, not an observational proof claim. It does not claim that standard cosmology or the Standard Model has been experimentally refuted, nor that particle masses and quantum numbers have already been fully derived. Attribution is required. Non-commercial reuse only. Commercial use, resale, sublicensing, relicensing, or removal of attribution requires explicit written permission from Yuuki Theory. Author / Theory Holder: Yuuki Theory ORCID: 0009-0003-5736-5297