What our existence is, which constitutes the crucial problem for us, living together in this “In-der-Welt-Sein.” However, Hegel seems give us a thread of guidance through his “Notion of Spirit,” dialectically expressed in this scheme : <“I” that is “We” and “We” that is “I”>. This is required so that the Absolute Substance becomes clear, in the unity of the different independent self-consciousness, but a convincing reason is not given. The reason why it is asked between <I> and <We >, not between <I> and <other(s)>, remains an issue. Face to face with this fact, we want to clarify our existence itself, analyzing the notion of “Inter-subjektivität,” which explains existence, for Husserl, in the relationship between “Individual and Individual,” with the notion of “Appräsentation,” and for Hiromatsu, in the relationship of <We as I and I as We>, with the notion of “Isomorphism” of “Inter-subjektivität.” Clarifying the relation between <I> and <We>, we expect to deduce the ontological meaning of existence, in the process of the “Inter-formation” of <I> and <We>.