  "Changing-look active galactic nuclei" (CLAGNs) are known to change their
apparent types between types 1 and 2, usually accompanied by a drastic change
in their luminosity on timescales of years. However, it is still unclear
whether materials in broad-line regions (BLRs) in CLAGNs appear and disappear
during the type-transition or remain at the same location while the line
production is simply activated or deactivated. Here we present our
X-ray-optical monitoring results of a CLAGN, NGC 3516, by Suzaku, Swift, and
ground telescopes, with our primary focus on the narrow Fe-K$\alpha$ emission
line, which is an effective probe of the BLR materials. We detected significant
variations of the narrow Fe-K$\alpha$ line on a timescale of tens of days
during the type-2 (faint) phase in 2013-2014, and conducted "narrow
Fe-K$\alpha$ reverberation mapping," comparing its flux variation with those of
the X-ray continuum from a corona and $B$-band continuum from an accretion
disk. We derived, as a result, a time lag of $10.1^{+5.8}_{-5.6}$ days
($1\sigma$ errors) for the Fe-K$\alpha$ line behind the continuum, which is
consistent with the location of the BLR determined in optical spectroscopic
reverberation mapping during the type-1 (bright) phase. This finding shows that
the BLR materials remained at the same location without emitting optical
broad-lines during the type-2 phase. Considering the drastic decrease of the
radiation during the type-transition, our result is possibly inconsistent with
the hotly-discussed formation models of the BLR which propose that the
radiative pressure from an accretion disk should be the main driving force.
