  The J-PARC is a hadron-accelerator facility to provide secondary beams of
kaons, pions, neutrinos, muons, and the others together with the primary proton
beam for investigating a wide range of science projects. High-energy hadron
physics can be studied by using high-momentum beams of unseparated hadrons,
which are essentially pions, and also primary protons. In this report, possible
experiments are explained on color transparency and generalized parton
distributions (GPDs). These projects are complementary to lepton-scattering
experiments at JLab, COMPASS/AMBER, and future electron-ion colliders. Because
of hadron-beam energies up to 30 GeV, the J-PARC is a unique facility to
investigate the transition region from the hadron degrees of freedom to the
quark-gluon one. It is suitable for finding mechanisms of the color
transparency. Such color-transparency studies are also valuable for clarifying
factorization of hadron-production processes in extracting the GPDs from actual
measurements. These studies will lead to the understanding of basic high-energy
hadron interactions in nuclear medium and to clarifications on the origins of
hadron spins, masses, and internal pressure mechanisms.
