The mechanism of the a bond cleavage of H2O, NH3, Me2C=O, H-2, CH4, BH3, and SiH4 on the Ge=O bond of germanone is examined by means of both quantum mechanical (QM) and molecular dynamics (MD) methods. The QM calculations show that the a bonds of all the substrates are heterolytically broken on the very largely polarized Ge=O bond. Before the a bond cleavage, the substrate at first approach the Ge=O germanium in the cases of H2O, Me2C=O, and NH3, and in contrast, the Ge=O oxygen in the cases of H-2, CH4, BH3, and SiH4. For the cases of H2O, NH3, and Me2C=O, a cluster in which the substrate coordinates to the Ge exists before the a bond cleavage, and this coordination of the substrate plays an important role on the heterolytic a bond cleavage. The QM-MD simulations are also conducted for the case of H2O, and they show that the kinetic energy of the H-2 coordinated cluster especially concentrates on the coordinated H2O oxygen to strongly oscillate the coordinate bond between the H2O oxygen and the Ge. This oscillation further enlarges just before the O-H a bond cleavage, and the kinetic energy of this oscillation would be transmitted to the normal mode of the O-H bond breaking. Thus, the coordination and the vibration of the H2O oxygen was thought to be an important driving force of the heterolytic cleavage of the O-H a bond in both electronic and dynamical aspects.