An application of our theory published in Prog.Theor. Phys.125, 359 (2011) entitled "Equations of Motion for the System of Interest under Time-Dependent Environment" is discussed. Its classical version is applied for the motion in s parameter space spanned by coordinates and momenta of nucleons which are expressed by the Gaussian wave packets following the spirit of fermion molecular dynamics. Derivation of time coarse-grained equation which describes macroscopic collective motion like relative motion between two nuclei in HI-DIC and fusion process is discussed.