  We present near- and mid-infrared observations on the shock-cloud interaction
region in the southern part of the supernova remnant HB 21, performed with the
InfraRed Camera (IRC) aboard AKARI satellite and the Wide InfraRed Camera
(WIRC) at the Palomar 5 m telescope. The IRC 4 um (N4), 7 um (S7), and 11 um
(S11) band images and the WIRC H2 v=1->0 S(1) 2.12 um image show similar
diffuse features, around a shocked CO cloud. We analyzed the emission through
comparison with the H2 line emission of several shock models. The IRC colors
are well explained by the thermal admixture model of H2 gas--whose
infinitesimal H2 column density has a power-law relation with the temperature
$T$, $dN\sim T^{-b}dT$--with n(H2) $\sim3.9\times10^4$ cm^{-2}, $b\sim4.2$, and
N(H2;T>100K) $\sim2.8\times10^{21}$ cm^{-2}. We interpreted these parameters
with several different pictures of the shock-cloud interactions--multiple
planar C-shocks, bow shocks, and shocked clumps--and discuss their weaknesses
and strengths. The observed H2 v=1->0 S(1) intensity is four times greater than
the prediction from the power-law admixture model, the same tendency as found
in the northern part of HB 21 (Paper I). We also explored the limitation of the
thermal admixture model with respect to the derived model parameters.
