  Inspired by Yoneya's recent work on D-brane field theory, we present the
constructive definition of this theory as a new dual model based on the
quantization of non-perturbative string gauged S-dualities and its spontaneous
breakdown. Our model is determined by one BRST quantization condition. Here, we
provide some testable conjectures, for example, that the partition function of
bosonic part of IIB matrix model and string partition functions of various
interactions including gravity are realized by the physical state and its
Goldstone modes.
