Dynamics of Affective Echo Chamber Formation and Escape in Multimodal Generative AI-Assisted Emotion Externalization ── An N=1 Autoethnography via Textual Close Reading, Narrative Resource Saturation, and Autonomous Boundary Setting

This paper serves as an individual Research Note based on the previously published overall architecture (Onkyo Protocol v2), systematically examining the mechanisms of affective amplification and the boundary conditions for loop termination and decentering in multimodal generative AI-assisted emotion processing. 【Abstract】Background: Self-directed emotion externalization utilizing generative AI circumvents interpersonal shame and social friction, enabling uninhibited affective expression. However, an AI system's uncritical acceptance (perceived sycophancy) introduces structural risks of establishing an "affective echo chamber" that aestheticizes and self-perpetuates distress. Methods: Employing an N=1 autoethnographic approach, this study conducts a textual close reading of the foundational track "Beyond the Swipe" (Swipe no Mukougawa) and phenomenologically analyzes production logs, prompt architectures, and termination dynamics across 36 tracks composed between January and May 2026. Results: 1. Internal Convergence: A parallel reduction of spatial scale (distant → proximal) and sensory modality embodiment (linguistic → visual → tactile), termed "Sensory Convergence," successfully bypassed psychological intellectualization, triggering acute cathartic collapse (weeping).2. Multi-Layered Autonomous Boundary Setting: In a low-friction AI environment, a subjective urgency arose that rumination could persist indefinitely past 100 tracks. The system was ultimately regulated via multi-tiered boundary conditions: - Five Stopping Conditions: (1) Autonomous cold-water protocol (cognitive control), (2) Subjective saturation of narrative resources (resource constraint), (3) Shortening of subjective emotional recovery time (affective state shift), (4) Self-preservation judgment (intrinsic boundary), and (5) A real-world relational crisis involving the current partner (external social pressure). - Decentering Trigger: The deliberate insertion of past verbatim dialogue (three distinct historical quotes) into a track generated from the ex-wife's perspective triggered a "Full-Counter Phenomenon" (a metaphor borrowed from combat sports denoting a decisive counter-strike that turns the other's real force back onto oneself), severely destabilizing self-centered narrative consistency and prompting narrative disengagement. Conclusion: The reduction of interactional friction by generative AI risks eliminating the natural stopping conditions historically imposed by human communication. Safety in high-gain AI environments depends not solely on model-side guardrails, but on the user's capacity for "Autonomous Boundary Setting"—the active re-implementation of artificial friction, real-world anchors, and genuine otherness. 【Keywords】Digital Therapeutics (DTx), Generative AI, Autoethnography, Computational Phenomenology, Human-AI Interaction (HAI), Sensory Convergence, Autonomous Boundary Setting, Therapeutic Friction, Affective Echo Chamber, Narrative Resource Saturation, Complicated Grief, Cognitive Defusion