Interpersonal touch, one of the most primitive social languages, is an excellent design element frequently used in interaction design. In this paper, we present a richer understanding of it by using spatial factors and social relations among people, which has rarely been explored in interactive systems. We designed an interactive installation called "TouchBranch" where players can move light between branches placed at various distances by connecting their bodies. The user studies were conducted with 21 groups consisting of intimates, acquaintances, and strangers. We observed a change in the interpersonal touch pattern and touch tolerance according to each factor. Interestingly, the effect of the social relation was dramatic, but that of the spatial factor was not quantitatively significant. Nevertheless, we discovered that spatial factor can influence the interpersonal touch experience. Based on the results, we discuss in this paper the influence of two factors on the interpersonal touch that stands out in the context of interactive systems.