This paper presents structure within the first system of Kasei-Theory as a non-modal readability maintainability architecture. The paper does not propose a theory of system, universal organization, completed integration, relational totality, finalized coherence, terminal configurational order, configuration-derived systematization, system-derived organization, organization-derived coherence, totality-derived order, or transcendental structural order. Instead, it fixes structure, constrained structure, configurational differentiation, local maintainability, unreadability, formal structure, and non-totality as distributed structural positions within constrained local readability maintainability. Structure is not treated as system, organization, totality, or completed coherence, but as constrained structure under which configurational differentiation remains locally maintainable without universal systematization, completed integration, relational order, terminal coherence, or total configurational closure. Structure does not establish system. Structure does not establish universal integration. Structure does not establish organization. Structure does not establish terminal configurational coherence. Structure remains fixed only as constrained structure within readability maintainability. This paper fixes only the local structural conditions under which configurational differentiation remains maintainable without transition into universal stabilization, completed continuity, configuration-derived systematization, system-derived organization, totality-derived order, or total configurational integration. No subject is presupposed. No universal structural system is established. No completed configurational integration is secured. No total configurational closure is completed. This paper is part of Kasei-Theory.