  Estimating a reliable covariance matrix for correlation functions of galaxies
is a crucial task to obtain accurate cosmological constraints from galaxy
surveys. We generate 2,000 independent lightcone mock luminous red galaxy
(LRGs) catalogues at $0.3 \leq z \leq 1.25$, designed to cover CAMIRA LRGs
observed by the Subaru Hyper Suprime-Cam Subaru Strategic Programme (HSC SSP).
We first produce full-sky lightcone halo catalogues using a COmoving Lagrangian
Acceleration (COLA) technique, and then trim them to match the footprints of
the HSC SSP S20A Wide layers. The mock LRGs are subsequently populated onto the
trimmed halo catalogues according to the halo occupation distribution model
constrained by the observed CAMIRA LRGs. The stellar mass ($M_{\star}$) is
assigned to each LRG by the subhalo abundance-matching technique using the
observed stellar-mass functions of CAMIRA LRGs. We evaluate photometric
redshifts (photo-$z$) of mock LRGs by incorporating the photo-$z$ scatter,
which is derived from the observed $M_{\star}$--photo-$z$-scatter relations of
the CAMIRA LRGs. We validate the constructed full-sky halo and lightcone LRG
mock catalogues by comparing their angular clustering statistics (i.e., power
spectra and correlation functions) with those measured from the halo catalogues
of full $N$-body simulations and the CAMIRA LRG catalogues from the HSC SSP,
respectively. We detect clear signatures of baryon acoustic oscillations (BAOs)
from our mock LRGs, whose angular scales are well consistent with theoretical
predictions. These results demonstrate that our mock LRGs can be used to
evaluate covariance matrices at large scales and provide predictions for the
BAO detectability and cosmological constraints.
