The properties of the new YN · YY interaction model ESC08 are studied on the basis of the G-matrix theory. G-matrix calculations in nuclear matter are performed in the cases of ΛN -, ΣN -, ΞN -a ndΛΛ -starting channels. In the ΛN case, the spin-spin and spinorbit terms are shown to be of reasonable strengths. The folding-model analyses are done extensively for observed spectra of Λ hypernuclei. The experimental energy spectra are nicely reproduced. The shell-model analyses for typical Λ hypernuclei are performed with the Gmatrix interactions. In the ΣN case, the repulsive values of UΣ are obtained owing to the effect of the quark Pauli-forbidden states which are taken into account phenomenologically in ESC08. In the ΞN case, the moderately attractive values of UΞ are obtained mainly due to the strongly attractive contributions in 3 S1 T =1 ΞN -ΛΣ -ΣΣ coupled states, which leads to extensive existence of Ξ hypernuclei. In the ΛΛ case, the BΛΛ values derived from ESC08 are found to be consistent with the experimental values.