This paper presents impossibility within the first system of Kasei-Theory as a non-modal readability maintainability architecture. The paper does not propose a theory of negation, absence, failure, contradiction, terminal exclusion, completed configurational collapse, operational incapacity, boundary-derived retention failure, or transcendental impossibility. Instead, it fixes impossibility, constrained non-fixability, configurational differentiation, local maintainability, unreadability, formal impossibility, and non-totality as distributed structural positions within constrained local readability maintainability. Impossibility is not treated as negation, absence, or failure, but as constrained non-fixability within readability maintainability under which configurational differentiation remains locally maintainable without universal negation, completed disappearance, operational failure, or total configurational closure. Impossibility does not establish negation. Impossibility does not establish absence. Impossibility does not establish failure. Impossibility does not establish terminal configurational collapse. Impossibility remains fixed only as constrained non-fixability within readability maintainability. This paper fixes only the local impossibility conditions under which configurational differentiation remains maintainable without transition into universal disappearance, completed exclusion, operational incapacity, boundary-derived retention failure, or total configurational integration. No subject is presupposed. No negative structure is established. No universal impossibility structure is secured. No total configurational closure is completed. This paper is part of Kasei-Theory.