(Proposal ID) S10A-123 (PI) Matsunaga, Noriyuki (Proposal Title) Chemical tagging by newly discovered tracers in the innermost Galaxy (Abstract) A serious scarcity of the observed samples in the inner Galaxy hampers our understanding of the formation and evolution of the Galactic bulge and the inner part of the Galactic disk. However, recent discoveries of new objects in the innermost Galaxy by large-scale decadal surveys as well as extensive surveys with 2-4 m-class telescopes finally enable us to unravel the chemical structure of this region. Here we propose to measure the metallicities as well as the key elemental ratios such as [O/Fe], for newly discovered objects: Cepheids and red supergiants , which are best probes for high-precision abundance studies through the Galactic scale. The target Cepheids have been discovered by our own survey, in particular, three of which resided within R_GC=1 kpc are the first Cepheids to be measured in such a central part of the Galaxy. We highlight two crucial issues: (1) chemical connection between the bulge and the innermost disk, and (2) the puzzling dip in the metallicity for the region 4< R_GC <6 kpc, which is reported very recently by Keck observation, but needs to be confirmed in view of its strong impact on the chemical evolution study of this innermost region. Combining the observed elemental features with our theoretical modeling , we aim to reveal the formation history of the Galactic disk and bulge in the framework of bulge secular evolution, which is strongly claimed by recent studies.