It seems that we are approaching a new chapter in the homebuilding industry, where the construction of new houses has drastically decreased, and the secondhand housing market is being activated. Therefore, we thought that planning design based on secondary (secondhand) distribution would become important for housing made by building contractors in the future. As opposed to a conventional house in which only the initial owner's family can live comfortably, which would then be taken over from these parents and lived in by their children, now we have planned and developed the concept of "a house that will be highly useful for diverse families forever," considering (1) good livability for a diverse range of families, (2) possibility of being taken over by or from other people and (3) high variability of living styles.