Histone H3-like variant which exclusively replaces conventional H3 in the nucleosome core of centromeric chromatin at the inner plate of the kinetochore. Required for recruitment and assembly of kinetochore proteins, mitotic progression and chromosome segregation. May serve as an epigenetic mark that propagates centromere identity through replication and cell division. Not required for chromosome segregation during meiosis. Forms a nucleosome-like histone octamer containing two molecules each of H2A, H2B, cpar-1 and H4 assembled in one cpar-1-H4 heterotetramer and two H2A-H2B heterodimers. Localizes to chromosomes during meiotic prometaphase I and metaphase I. Upon cleavage at the onset of anaphase I, the C-terminus remains localized to chromosomes. The cleaved form transiently associates with chromosome but not centromeres during embryonic mitosis. Cleaved at the onset of meiotic anaphase I, likely by separase sep-1. Belongs to the histone H3 family.