  Through $B\bar{B}$ mixing system, one can construct an asymmetry which
naively seems to be a time reversal (T) odd quantity. In this article, the two
processes $(\mathrm{a})\: B_-\rightarrow \bar{B^0}$ and $(\mathrm{b})\:
\bar{B^0}\rightarrow B_-$ are used to construct the event number asymmetry. The
CP violation of Kaon system denoted as $\epsilon_K$ contributes to observables
and we evaluate the contribution from $\epsilon_K$ explicitly. The asymmetry is
formulated with phase convention independent parameters which are invariant
under redefinition of phase of quark fields. The overall factors of the time
dependent decay rates are taken into account in this article. Furthermore, we
suggest conditions for the asymmetry to be a T-odd quantity. The one of such
conditions arises due to the difference of overall factors which form the
asymmetry.
