  We analyze the neutrino Yukawa matrix by considering three constraints: the
out-of-equilibrium condition of lepton number violating process responsible for
leptogenesis, the upper bound of branching ratio of lepton flavor violating
decay, and the prediction of large mixing angles using the see-saw mechanism.
In a certain parametrization with bi-unitary transformation, it is shown that
the structure which satisfies the constraints can be characterized by only
seven types of Yukawa matrices. The constraint of the branching ratio of LFV
turns out as a redundant one after applying other two constraints. We propose
that this parametrization can be the framework in which the CP asymmetry of
lepton number violating process can be predicted in terms of observable
neutrino parameters at low energy, if necessary, under assumptions following
from a theory with additional symmetries. There is an appealing model of
neutrino Yukawa matrix considering the CP asymmetry for leptogenesis and the
theoretical motivation to reduce the number of free parameters.
