  We are reporting on a search for flavour-changing neutral current decays $D^0
\to \mu^+ \mu^-$ and $D^0 \to e^+ e^-$, and for lepton-flavour violating decays
$D^0 \to e^\pm \mu^\mp$, the measurement of $D^+_{(s)} \to K_S^0 \pi^+$ and
$D^+_{(s)}\to K_S^0 K^+$ branching fractions, and the search for CP violation
in $D^+_{(s)} \to K_S^0 \pi^+$ and $D^+_{(s)} \to K_S^0 K^+$ decays. The
analyses are based on 600 fb$^{-1}$ to 700 fb$^{-1}$ of data collected in
$e^+e^-$ collisions at the centre-of-mass (CM) energy of the $\Upsilon(4S)$
resonance and 60 MeV below by the Belle detector at the KEKB collider.
