  Complex Fe-K emission/absorption line features are commonly observed in the
6--11 keV band from Active Galactic Nuclei (AGN). These features are formed in
various physical components surrounding the black holes. The Narrow-Line
Seyfert 1 (NLS1) galaxy Mrk 766, in particular, exhibits characteristic
blue-shifted Fe-K absorption lines caused by the ultra-fast outflow (UFO), and
a broad Fe-K emission line, as well as variable absorbers partially covering
the X-ray emitting region. We re-analyze the Mrk 766 archival data of
XMM-Newton, NuSTAR, and Swift to investigate the origin of the Fe-K line
feature and the 0.3--79 keV energy spectral variation. We have found that the
spectral variation in $\lesssim$10 keV is primarily explained by the variable
partial covering of the central X-ray source by multi-layer absorbing clouds.
The Fe-K line feature consists of the blue-shifted absorption lines due to the
UFO, a narrow emission line from the distant material, a broad emission line
from the inner-disk reflection, and a slightly broadened weak emission line at
around 6.4--6.7 keV whose equivalent width is $\sim$0.05 keV. The last one is
presumably due to the resonance scattering in the UFO out of the line-of-sight,
as predicted by a Monte Carlo simulation based on the hydrodynamical UFO
modeling. We suggest that the seemingly complex Fe-K line features and the
X-ray energy spectra of Mrk 766 are explained by a moderately extended central
X-ray source around a Schwarzschild black hole, an optically thick accretion
disk with a truncated inner-radius, the UFO, multi-layer partial covering
clouds, and a torus.
