  We propose a universal mixing hypothesis between quark and lepton sectors at
high energy scale (probably GUT scale) where quark-lepton universality holds.
Namely in the charged lepton diagonal base, all the other mass matrices for up
and down quarks and neutrinos are diagonalized by the same unitary matrix
except for the phase elements. Thanks to this hypothesis, the observed values
of the Cabibbo-Kobayashi-Maskawa (CKM) quark mixing matrix and the mixing
angles $\theta_{12}$ and $\theta_{23}$ in the Maki-Nakagawa-Sakata (MNS) lepton
mixing matrix can predict the unknown magnitudes of the mixing angle
$\theta_{13}$ and of the CP violating Dirac phase $\delta $ in the MNS matrix.
Their allowed regions are rather narrow, $0.036<{sin}\theta_{13}<0.048$ and
$6^\circ<\delta <12^\circ$.
