The First Star-by-star N-body/Hydrodynamics Simulation of Our Galaxy Coupling with a Surrogate Model. - Keiya Hirashima; Michiko S. Fujii; Takayuki R. Saitoh; Naoto Harada; Kentaro Nomura; Kohji Yoshikawa; Yutaka Hirai; Tetsuro Asano; Kana Moriwaki; Masaki Iwasawa; Takashi Okamoto; Junichiro Makino (CoRR, 2025)