  Novel electronic order is found theoretically for a system where even number
of localized electrons per site are coupled with conduction electrons. For
precise quantitative study, a variant of the Kondo lattice model is taken with
crystalline electric field (CEF) singlet and triplet states for each site.
Using the dynamical mean-field theory combined with the continuous-time quantum
Monte Carlo method, a staggered order with alternating Kondo and CEF singlets
is identified for a case with one conduction electron per site being
distributed in two conduction bands each of which is quarter-filled. This
electronic order accompanies a charge density wave (CDW) of conduction
electrons that accumulate more on Kondo-singlet sites than on CEF-singlet
sites. Possible relevance of the present order to the scalar order in
PrFe$_4$P$_{12}$ is discussed.
