Conventionally, consciousness is thought to be a result of the brain’s neuronal activity, and much research activity is focused along this line of thought; however, circumstantial evidence has not yet been obtained. As an alternative, I posit that the multidimensional picture of the universe can be important in seeking the origin of the consciousness outside the brain. Herein, I hypothesize the existence of a new particle called the parasite fermion. This is a material particle that exists in the extra dimension, i.e., outside our four-dimensional universe. Further, the differences in material properties of the parasite fermions and the particles that exist in our universe, termed as host fermions, and the mechanism that causes these differences are reviewed in this paper. Moreover, it is hypothesized that the aforementioned mechanism renders the parasite fermion invisible, although they exist around us. The question is what happens if we apply the parasite fermion concept to the mind–body problem. In the regard, the parasite fermion model has the possibility to help clarify the origin of conciseness being outside the brain.