21 KE is a movie discussing about self-existence. We always question life, achieve value or meaning of life, keep looking for different referencing system to define self-existence; however, the world may not be like what we cognize, it could be a complicated mixture of multivariate and multiple systems which coexist and parallel. When we are trying to care, ultimately, we will realize that we are at the most marginal place of the world; we stand on the cliff, and we are always embarrassed. We are on the way to find the truth, we can feel its existence, but can never get close to it. The world is round; our life is like pi; but our continuous approaches turn to be endless cycles.