To address construction challenges, Kajima Corporation has implemented "Proactive Design," an innovative approach integrating detailed construction knowledge from the earliest design stages. This method fundamentally prevents issues related to quality, inconsistencies, cost overruns, and rework. For instance, after Phase 1, condensation issues arose only on the north façade, despite identical floor plans. In Phase 2, we used its integrated design-build capabilities to resolve this issue through early-stage simulations. A LOD 500 model is prepared at the commencement of construction, enabling BIM-based inspections 365 days earlier than standard, thereby mitigating postconstruction risks. During construction, Digital Prototypings ensure real-time consistency. Furthermore, Kajima promotes modularization at the design stage, involving engineers, subcontractors, and fabricators in a seamless integrated model. This approach aims to elevate industry standards and drive progress toward a sustainable future.