  We have performed systematic studies of narrow Fe-K line (6.4 keV) flux
variability and Ni-K line intensity for Seyfert galaxies, using {\em Suzaku}
and {\em XMM-Newton} archival data. Significant Fe-K line variability of
several tens percents was detected for a pair of observations separated by
1000--2000 days (Cen A, IC 4329 A, NGC 3516, and NGC 4151) and 158 days (NGC
3516). These timescales are larger by a factor of 10--100 than the inner radius
of torus, consistent with the view that X-ray reflection by torus is a main
origin of a narrow Fe-K line. Ni-K line was detected with $>2\sigma$ level for
the Circinus galaxy, Cen A, MRK 3, NGC 4388, and NGC 4151. A mean and variance
of Ni-K$\alpha$ to Fe-K$\alpha$ line intensity ratio are 0.066 and 0.026,
respectively. Comparing this with the Monte-Carlo simulation of reflection, Ni
to Fe abundance ratio is 1.9$\pm$0.8 solar. We discuss the results and
possibility of Ni abundance enhancement.
