  We explore the elemental abundance features of metal-rich disk stars,
highlighting the comparisons made with those of the recently revealed Galactic
bulge stars. A similarity between two of the comparisons leads to a new
theoretical picture of the bulge-disk connection in the Galaxy, where a
supermassive black hole resides at the center. We postulate that a metal-rich
outflow, triggered by feedback from a black hole, was generated and quenched
the star formation, which had lasted several billion years in the bulge. The
expelled gas cooled down in the Galactic halo without escaping from the
gravitational potential of the Galaxy. The gas gradually started to accrete to
the disk around five billion years ago, corresponding to the time of sun's
birth, and replaced a low-metallicity halo gas that had been accreting over
nearly ten billion years. The metal-rich infalling gas, whose elemental
abundance reflects that of metal-rich bulge stars, mixed with the interstellar
gas already present in the disk. Stars formed from the mixture compose the
metal-rich stellar disk. This scheme is incorporated into models for chemical
evolution of the disk. The resultant elemental features are compatible with the
observed abundance trends of metal-rich disk stars, including the upturning
feature exhibited in some [X/Fe] ratios, whose interpretation was theoretically
puzzling. Furthermore, the predicted abundance distribution function of disk
stars covers all observational facts to be considered: (i) the deficiency of
metal-poor stars, (ii) the location of peak, and (iii) the extended metal-rich
tail up to [Fe/H] ~ +0.4.
