Monolayer structures of a chiral mesogen, (R)- or (S)-[4'-(1-methylheptyloxy)-3'-nitrobiphenyl-4yl] 4-(trans-5-decenyloxy) benzoate, adsorbed on graphite were investigated by molecular dynamics simulations to clarify the mechanism of chirality inductions from chiral mesogens to chiral monolayers. We propose a molecular model that is based on coupling between the up-down symmetry breaking and the molecular tilt direction symmetry breaking of the monolayer. From the proposed model, we further predict alternative reversal of the two dimensional chirality of the monolayer when the chiral carbon is shifted along alkyl chain. This is a two-dimensional analogue of the "odd-even" effect on twist sense reversal in bulk chiral nematic systems.