  We investigate a 5d gauge theory on $S^1$ with point interactions. The point
interactions describe extra boundary conditions and provide three generations,
the charged lepton mass hierarchy, the lepton flavor mixing and tiny
degenerated neutrino masses after choosing suitable boundary conditions and
parameters. The existence of the restriction in the flavor mixing, which
appears from the configuration of the extra dimension, is one of the features
of this model. Tiny Yukawa couplings for the neutrinos also appears without the
see-saw mechanism nor symmetries in our model. The magnitude of CP violation in
the leptons can be a prediction and is consistent with the current experimental
data.
