  In rare $B$ meson decays $B\rightarrow K \ell^+ \ell^-$, a possible
contribution of $\ell^+\ell^-$ emission via photon from the "spectator" quark
$q$ ($q=u,d$) in the $B$ meson $(q\bar{b})$ is investigated in addition to the
conventional one $\bar{b} \rightarrow \bar{s} +\gamma \rightarrow
\bar{s}+\ell^+ + \ell^-$. If such a contribution is sizable compared with the
standard estimation of $B\rightarrow K \ell^+ \ell^-$, we will observe visible
difference between $d \Gamma(B^0\rightarrow K^0 \ell^+ \ell^-)/d q^2$ and $d
\Gamma(B^+\rightarrow K^+ \ell^+ \ell^-)/d q^2$ in $q^2$ dependence ($q^2
\equiv m_{\ell\ell}^2$). Besides, as a result of the interference between the
conventional one and a new one, a dip appears in $d \Gamma(B\rightarrow K
\ell^+ \ell^-)/d q^2$ at a small region of $q^2$. The interference effect in
the $B^0$ decay will also be observed differently from that in the $B^+$ decay.
The calculation is done based on a semi-classical approach, a valence quark
model. In the present model, the photon emission from the spectator quark $q$,
$d \rightarrow d+\gamma$ ($u \rightarrow u+\gamma$) is independent of the
$b$-$s$ transition mechanism, and the characteristic results are due to a
straightforward estimate of the quark propagator which cannot be incorporated
into the factorization method. The model is not a valence quark "dominant"
model, so that, for example, the valence quarks in the final state carry only
$24\%$ of the energy-momentum of the kaon.
