There are large-scale green spaces in Tokyo that were never protected and have lost their original function due to war and urbanization. Today, as Tokyo's aging population, increasing flooding, and other issues become more serious, we will focus on Toyama Park, and Toyama Heights, a metropolitan apartment complex, and the Toyama 3-chome residential area in Shinjuku-Ku, Tokyo, a large-scale green space that has lost its function. The history of the target sites as green spaces and their relationship with water will be investigated, and three revitalization methods will be used to create a new urban framework where people, water, and greenery intersect, aiming to promote multi-generational interaction and strengthen the urban ecosystem. Through the spread effect of green spaces, we will design a place that will be the first step toward a green space covering Tokyo.