Sociality is difined topologically as a tabu system, which corresponds to a region involving some islets in it. Generally the members of a society are limited to the ones who are recognized by their moving abilities in it, so the number of islets may be under saturated in the region. On the contrary the number of islets may be oversaturated in the region in a capitalistic society. Thus there are two types of social conflicts. At separation of a society there arises over saturation of tabu in both parts of it, while at annexation of societies there are produced under saturation of tabu in the connected society. In this connection topological approaches to Japanese custom are discussed. The theory indicates an occult region besides a foetus one too, which contains ought instead of Tabu.