Structures of a typical Ξ-hypernucleus have been calculated using the Ξ-N G-matrix interactions deduced from the existing meson theoretical potential models. In anticipation of the priority experiment to be done at the J-PARC facility, the many-body wave functions with nuclear core-excitation effects have been used for the DWIA estimates of the (K−,K+) reaction spectra of Ξ-hypernuclear productions. The predictions suggest that a clear Ξ bound state peak, if confirmed experimentally, provides us with novel restriction on the interaction strength and especially its spin-spin property of the Ξ-N potentials.