On higher ground in Rikuzentakata, a “castle” serves as both senior housing and community plaza—filling a void left after the 2011 tsunami. Planned around a central plaza using tatami logic, housing clusters form courtyards that evolve into farms, gardens, or gathering spaces. This flexible layout restores communal autonomy while fostering intergenerational exchange. Built with vernacular techniques—displaced soil, local timber, thatch—the low-cost, low-tech structures invite volunteer participation and allow sustainable renewal. Sliding doors, ramps, and engawa porches ensure accessibility and interaction. The central hall doubles as a kitchen, event space, or refuge, reinforcing the complex as a protector and social heart of the community.