The focus of this study is NEXT21, an experimental housing complex by Osaka Gas, where residential experiments began in 1994—now reaching 30 years (as of 2024).
In examining changes in unit sizes over these three decades, I found that with each layout modification, the private floor area has actually decreased.

This appears to stem from differences in approval processes between extensions and reductions during renovation.
In any case, rather than viewing this SI system—where private space tends to shrink—as a “negative,” this proposal reinterprets it through a kind of Copernican shift: focusing instead on the increase in shared space that accompanies the reduction.

By transforming this expanded common area into spaces for small-scale commerce, the project envisions a live-work environment.
Using the SI system, residents can each develop their own small businesses, forming a new economic sphere and community.