The "Ki no iE" is a small Home overlooking the Hat Rock in Abashiri given to a boy with Prader-Willi Syndrome. A growing appetite, developmental delay, and short stature commonly characterize the syndrome. We planned life in this home to become a natural diet and exercise regimen. For example, we designed a "hallway-integrated kitchen" that is always organized for others to see and a "variety of steps" and "bouldering wall" to encourage natural exercise in daily life. Also, the sight of the Ainu people praying on Hat Rock synchronizes with everyone's wish for a peaceful life at the entrance.