"Insomniacs After School" centers on two high school students, Ganta Nakami and Isaki Magari, who both suffer from chronic insomnia. Their paths cross when they discover each other in the school’s abandoned observatory, a place they separately use as a refuge to escape their sleepless nights. Nakami, a reserved and academically driven student, struggles with the physical and emotional toll of his insomnia, while Magari, more outgoing and creative, copes with her condition through humor and a passion for photography.

The narrative explores their growing bond as they form a tentative friendship, sharing their experiences and finding solace in each other’s company. They decide to revive the school’s astronomy club, using the observatory as a base to stargaze and document their nights. This shared activity becomes a therapeutic outlet, allowing them to confront their insomnia and the underlying anxieties that contribute to it.

As the story progresses, their relationship deepens, blending moments of quiet introspection with lighthearted interactions. The manga delves into their personal struggles, including Nakami’s strained family dynamics and Magari’s health concerns, which add layers of complexity to their characters. The observatory serves as a symbolic space where they can escape the pressures of daily life and connect with something larger than themselves, whether through the stars or their shared experiences.

The series balances its exploration of insomnia and mental health with themes of friendship, self-discovery, and the beauty of finding connection in unexpected places. The pacing is deliberate, allowing the characters’ growth and the development of their relationship to unfold naturally. Through its grounded storytelling and relatable characters, "Insomniacs After School" offers a poignant and heartfelt portrayal of two individuals navigating the challenges of insomnia while finding meaning and companionship in each other.