  We analyze the high-resolution emission spectrum of WASP-33b taken using the
High Dispersion Spectrograph (R\,$\approx$\,165,000) on the 8.2-m Subaru
telescope. The data cover $\lambda$\,$\approx$\,$6170$-$8817$\,\AA, divided
over 30 spectral orders. The telluric and stellar lines are removed using a
de-trending algorithm, {\sc SysRem}, before cross-correlating with planetary
spectral templates. We calculate the templates assuming a 1-D plane-parallel
hydrostatic atmosphere including continuum opacity of bound-free H$^{-}$ and
Rayleigh scattering by H$_{2}$ with a range of constant abundances of Fe\,{\sc
i}. Using a likelihood-mapping analysis, we detect an Fe\,{\sc i} emission
signature at 6.4-$\sigma$ located at $K_{\mathrm{p}}$ of
226.0\,$^{+2.1}_{-2.3}$\,km\,s$^{-1}$and $v_{\mathrm{sys}}$ of
-3.2\,$^{+2.1}_{-1.8}$\,km\,s$^{-1}$ -- consistent with the planet's expected
velocity in the literature. We also confirm the existence of a thermal
inversion in the day-side of the planet which is very likely to be caused by
the presence of Fe\,{\sc i} and previously-detected TiO in the atmosphere. This
makes WASP-33b one of the prime targets to study the relative contributions of
both species to the energy budget of an ultra-hot Jupiter.

Earth and Planetary Astrophysics