AbstractThis paper evaluates the design development process of the Sendai City New Music Hall, a large-scale public project with a confirmed total cost of 64.6 billion JPY as of January 2026. Given the project’s scale relative to Sendai City (population ~1 million) and Miyagi Prefecture (population ~2 million), we apply international standards—ISO 9001 for quality management and ISO 3382 for architectural acoustics—to identify critical design parameters and mitigate information asymmetry. Utilizing a data-driven approach standardized through digital technology (Google NotebookLM), the research visualizes which design elements are determinable from current public records. We specifically highlight the risks of “regulatory decoupling” and the “support dilemma,” where administrative overhead potentially compromises actual site quality. This study serves as a reproducible framework for citizen-led verification of public infrastructure validity. Declarations: Neutrality, Intent, and Conflict of Interest Statement of Neutrality and Purpose: This study has been conducted as Citizen Science from a strictly neutral standpoint. The primary objective of this research is to establish a technical and objective record (technical record) to serve as a resource for future reflection and verification regarding the trajectory of the Sendai City New Music Hall project. Non-Criticism Policy: The analysis presented herein is based on academic and technical evidence; it is not intended to criticize any specific administrative body, design organization, contractor, or individual involved in the project. The focus remains on the evaluation of quality management frameworks and data-driven transparency. Disclosure of Conflict of Interest (COI): The authors declare that there are no conflicts of interest (COI). Neither the authors nor the underlying research have any financial, personal, or organizational interests in the administrative bodies or private entities associated with this construction plan.