Generational Debt and the Structural Deficit of Cultural Infrastructure: A Multi-Disciplinary Socio-Economic Evaluation of the 64.6 Billion Yen Sendai Music Hall Project (2026–2050)

The municipal government of Sendai is advancing a 64.6-billion-yen project for a 2,000-seat "Music Hall and Disaster Memorial Complex." This study provides a rigorous evaluation by synthesizing (1) a 567-pattern exhaustive Cost-Benefit Analysis (CBA) fixed to the 2050 RESAS demographic horizon; (2) a management accounting deconstruction of the "structural deficit model"; and (3) primary field audits of geographic redundancy. The analysis reveals that the working-age population in Miyagi has been in continuous decline since 2005, making large-scale fixed-cost investments statistically irrational. Furthermore, empirical evidence from on-site surveys confirms that existing infrastructure within a 5-minute radius, such as Tohoku University’s Hagi Hall, is bypassed even by its own resident organizations, undermining the project's justification. This paper concludes that the current plan represents a catastrophic social loss that prioritizes symbolic "hard" infrastructure over essential "soft" cultural capital and future fiscal stability.