  We report results on the search for $B_s\to\eta^{\prime}\eta$ decay, and the
searches for $B^0\to\textrm{invisible}$ and $B^0\to\textrm{invisible}+\gamma$
decays. The former result is based on a data sample of $121.4~\textrm{fb}^{-1}$
recorded at the $\Upsilon(5S)$ resonance while the later results are obtained
from a $711~\textrm{fb}^{-1}$ of data sample collected at $\Upsilon(4S)$
resonance with the Belle detector at the KEKB $e^+e^-$ collider. We observe no
significant signal for the decays and set upper limit on their branching
fractions at 90\% confidence level of
$\mathcal{B}(B_s\to\eta^{\prime}\eta)<7.1\times 10^{-5}$,
$\mathcal{B}(B^0\to\textrm{invisible})<7.8\times 10^{-5}$ and
$\mathcal{B}(B^0\to\textrm{invisible}+\gamma)<1.6\times 10^{-5}$.
