  We propose a scenario for bottom-up gravity dual picture of QCD-like
theories, which consists of two near-AdS$_5$ domains separated by the ``domain
wall'' at which the effective coupling relatively rapidly switches from small
perturbative value at its UV side to strong at its IR side. Its consequence are
corresponding jumps in 5-d masses of the bulk fields, related to different
anomalous dimensions of the corresponding operators. Inclusion of both weakly
and strongly coupled parts of bulk wave functions allows for consistent
inclusion of QCD hard processes.
  We further discuss how transitions from strong to weak coupling in hard
observables should look like, exemplified by pion diffractive dissociation,
which seems to show this transition experimentally. Then we propose a dynamical
mechanism for this jump related to instantons, which are point-like bulk
objects located at/near the domain wall. We further argue that in the limit of
large number of colors $N_c\to\infty$ the "domain wall" is becoming a true
singularity. Instanton-induced contributions to correlators and partition
function of the instanton ensemble is reformulated in the $AdS_5$ language.
Among other applications are lowest mesons as collective vibrations of the
``domain wall''.
