Introduction: Japan, one of the world’s most aged societies, faces unprecedented wealth management challenges. Trillions of yen in financial assets are held by elderly investors, and cognitive decline can increase management difficulties. Bloomberg coined the term “Dementia Money” to describe assets potentially affected by age-related cognitive decline, which could lead to underutilization, mismanagement, or frozen funds. This trend affects not only individual and family wealth security but may also influence capital market liquidity and resource allocation. With aging accelerating, strategic wealth planning, risk mitigation, and ensuring secure asset management and inheritance are increasingly important.