Near yrast positive-parity states of particle-hole nuclei around ${}^{100}$Sn have been studied and found mainly to be the coupling of ${g}_{9/2}$ valence-proton holes to the ${d}_{5/2}$ and ${g}_{7/2}$ valence-neutron particles. The much higher excitation energy for a stretched coupled state involving $\ensuremath{\nu}{g}_{7/2}$ rather than $\ensuremath{\nu}{d}_{5/2}$ indicates that level structures of particle-hole nuclei around ${}^{100}$Sn might be dominated by the $T=1$ channel of proton-neutron residual interaction. The near yrast states are compared with the results of shell model calculations in the model space of $\ensuremath{\pi}{({p}_{1/2},{g}_{9/2})}^{\ensuremath{-}1\ensuremath{-}\ensuremath{-}4}$ and $\ensuremath{\nu}{({d}_{5/2},{s}_{1/2},{d}_{3/2},{g}_{7/2},{h}_{11/2})}^{1\ensuremath{-}3}$ by using the dominant $T=1$ channel proton-neutron quadrupole interaction; and the reasonable agreement with each other gives indirect proof of it being responsible for level structures of particle-hole nuclei around ${}^{100}$Sn.