  We study a kaehler potential K of a one parameter family of Calabi-Yau d-fold
embedded in CP^{d+1}. By comparing results of the topological B-model and the
data of the CFT calculation at Gepner point, the K is determined unambiguously.
It has a moduli parameter psi that describes a deformation of the CFT by a
marginal operator. Also the metric, curvature and hermitian two-point functions
in the neighborhood of the Gepner point are analyzed. We use a recipe of tt^{*}
fusion and develop a method to determine the K from the point of view of
topological sigma model. It is not restricted to this specific model and can be
applied to other Calabi-Yau cases.
