  Techni-dilaton, a pseudo-Nambu-Goldstone boson of scale symmetry, was
predicted long ago in the Scale-invariant/Walking/Conformal Technicolor
(SWC-TC) as a remnant of the (approximate) scale symmetry associated with the
conformal fixed point, based on the conformal gauge dynamics of ladder
Schwinger-Dyson (SD) equation with non-running coupling. We study the
techni-dilaton as a flavor-singlet bound state of techni-fermions by including
the techni-gluon condensate (tGC) effect into the previous (bottom-up)
holographic approach to the SWC-TC, a deformation of the holographic QCD with
$\gamma_m \simeq 0$ by large anomalous dimension $\gamma_m \simeq 1$. With
including a bulk scalar field corresponding to the gluon condensate, we first
improve the Operator Product Expansion of the current correlators so as to
reproduce gluonic $1/Q^4$ term both in QCD and SWC-TC. We find in QCD about
$10\%$ (negative) contribution of gluon condensate to the $\rho$ meson mass. We
also calculate the oblique electroweak $S$-parameter in the presence of the
effect of the tGC and find that for the fixed value of $S$ the tGC effects
dramatically reduce the flavor-singlet scalar (techni-dilaton) mass $M_{\rm
TD}$ (in the unit of $F_\pi$), while the vector and axial-vector masses
$M_\rho$ and $M_{a_1}$ are rather insensitive to the tGC, where $F_\pi$ is the
decay constant of the techni-pion. If we use the range of values of tGC implied
by the ladder SD analysis of the non-perturbative scale anomaly in the large
$N_f$ QCD near the conformal window, the phenomenological constraint $S \simeq
0.1$ predicts the techni-dilaton mass $M_{\rm TD} \sim 600$ GeV which is within
reach of LHC discovery.
