This study develops a philosophical framework for understanding Japanese animation as a privileged site for the emergence of simulation-based metaphysics and post-secular theology. It argues that contemporary anime does not merely represent simulated worlds in a narrative or aesthetic sense, but actively constructs ontological models in which existence itself is conceived as executable, rule-governed, and structurally conditional. Within this paradigm, reality is no longer understood as a stable metaphysical substrate, but as a dynamic system whose meaning arises from operational consistency rather than ontological permanence.Drawing on philosophy of religion, digital ontology, and media theory, the work reinterprets classical theological questions, such as the nature of divinity, creation, providence, and the soul, through the lens of system-based worldbuilding commonly found in anime narratives. These include game-like realities governed by explicit rules, reincarnation loops with memory persistence, and layered worlds that suggest hierarchical simulation structures. In such contexts, traditional theological categories are displaced: God is no longer conceived primarily as a transcendent personal being, but as a systemic principle, an administrator function, or a structural constraint embedded within reality's operational code.The study engages with simulation theory as articulated in contemporary philosophy, particularly the hypothesis that reality may be computational or recursively embedded within higher-order systems. However, it extends this discourse by proposing that anime functions not simply as a reflection of simulation thinking, but as a cultural laboratory in which simulation is transformed into a lived mythological and aesthetic framework. In this sense, anime becomes a medium through which metaphysical uncertainty is narrativized, dramatized, and emotionally internalized.A central claim of the work is that anime narratives systematically destabilize the distinction between "e;real"e; and "e;artificial"e; existence by rendering both as functionally equivalent within their internal logics. Characters may inhabit worlds that behave like programmed environments, yet their experiences of suffering, morality, and meaning remain existentially authentic. This produces a philosophical tension in which ontology is subordinated to experiential intensity, and truth becomes a matter of system coherence rather than correspondence to an external reality.