  We construct a new model with exponential mass hierarchy by starting with the
Einstein-Hilbert action with the cosmological constant in five dimensions plus
an action describing many domain walls in four dimensions. The model includes
many hidden sectors and one visible sector, and each four-dimensional domain
wall, that is, 3-brane, interacts with one another through only a gravitational
interaction and realizes many universe cosmology inspired by D-brane
perspective. It is shown that in the present model only even numbers of domain
walls are allowed to locate in five dimensional space-time and the validity of
Randall-Sundrum scenario, which explains mass hierarchy between the Planck mass
and the electro-weak scale in our world, depends on a relative relation between
our world and hidden worlds.
