Our results of charm physics in
$N_f=2+1$ lattice QCD are presented.
The calculation is performed on configurations generated using Iwasaki gauge and six stout smeared $O(a)$-improved Wilson quark actions with the smearing parameter $\rho=0.1$
on a $96^4$ lattice at $\beta=1.82$ ($a^{-1} = 2.3$~GeV) with the spatial extent $L=8.1$~fm. The pion mass at the simulation point is almost physical, $m_\pi=146$~MeV, extrapolated to the physical point by use of reweighting.
The relativistic heavy quark action is utilized for the charm quark.
We exhibit the charmed spectrum and the charm quark mass, focusing on stout smearing influence.