Shinji, a perpetually exhausted student plagued by relentless insomnia, finds himself wandering the nocturnal streets in desperation when sleep refuses to come. A chance encounter with his homeroom teacher, Umi, leads to an unexpected conversation about his struggles—one that neither can openly pursue given the constraints of their professional relationship. Unwilling to abandon him, Umi devises an unconventional solution: meeting him under the guise of a different persona during their midnight outings. What unfolds is a series of clandestine evenings where the boundaries between student and mentor blur, offering Shinji solace and connection in the quiet hours when the world sleeps.