  We explore the heavy-quark mass region above the charm mass using M\"obius
domain-wall fermions on fine lattices at $a = 0.080$, $0.055$, and $0.044$ fm.
We examine masses and decay constants using a series of heavy quark masses up
to 3 times the charm quark. We analyze the cutoff effects for heavy quarks
above the charm and account for the leading order discretization effects using
ideas from HQET. We extrapolate to the bottom quark mass and report preliminary
results for $f_{B}$ and $f_{B_s}$
