Trusts and adult guardianship in Japan: balancing asset protection and autonomy in a super-aging society

Abstract This article examines the role of trusts in the Japanese adult guardianship system in the context of a rapidly aging society. Japan has developed two distinctive mechanisms: the Guardianship Support Trust (Kōken Seido Shien Shintaku), designed to safeguard the property of persons under adult guardianship, and the Family Trust (Kazoku Shintaku), which enables flexible asset management by family members and is increasingly used as an alternative to adult guardianship. While these mechanisms enhance asset protection, they also raise concerns about the potential misuse of trust property and the marginalization of the individual’s will. This article argues that a combination of voluntary guardianship and professionally administered trusts may provide a more balanced framework that respects both asset protection and individual autonomy.