  A powerful tool to probe the gas content at high redshift is the [C II] 158
$\mu$m sub-millimeter emission line, which, due to its low excitation potential
and luminous emission, is considered a possible direct tracer of star forming
gas. In this work we investigate the origin, evolution and environmental
dependencies of [C II] 158 $\mu$m emission line, as well as its expected
correlation with stellar mass and star formation activity of the high-redshift
galaxies observed by JWST. We use a set of state-of-the-art cold-gas
hydrodynamic simulations (ColdSIM) with fully coupled time-dependent atomic and
molecular non-equilibrium chemistry and self-consistent [C II] emission from
metal enriched gas. We accurately track the evolution of H I, H II and $H_2$ in
a cosmological context and predict both global and galaxy-based [C II]
properties. For the first time, we predict the cosmic mass density evolution of
[C II] and find that it is in good agreement with new measurements at redshift
z = 6 from high-resolution optical quasar spectroscopy. We find a correlation
between [C II] luminosity, $L_{[C II]}$, and stellar mass, consistent with
results from ALMA high-redshift large programs. We predict a redshift evolution
in the relation between $L_{[C II]}$ and the star formation rate, SFR, and
provide a fit to relate $L_{[C II]}$ to SFR which can be adopted as a more
accurate alternative to the currently used linear relation. Our findings
provide physical grounds to interpret high-redshift detections in contemporary
and future observations, such as the ones performed by ALMA and JWST, and to
advance our knowledge on structure formation at early times.
