"Tsuki Kagerō" is a supernatural drama that intertwines themes of memory, identity, and the passage of time. The narrative centers on a young man named Haruto, who discovers he possesses the ability to perceive and interact with fragments of memories left behind by others. These memories manifest as ethereal, moonlit visions, often tied to significant emotional events in people's lives. Haruto's ability draws him into the lives of various individuals, each grappling with unresolved emotions or regrets tied to their past.

The story unfolds in a small, rural town where Haruto encounters a mysterious girl named Satsuki, who appears to be connected to the phenomenon of the lingering memories. Satsuki's presence is enigmatic, and her own past becomes a focal point as Haruto delves deeper into the town's secrets. Through his interactions with Satsuki and others, Haruto begins to uncover the truth about the memories he sees, which are tied to a celestial event known as the "Tsuki Kagerō," a rare lunar phenomenon said to grant glimpses into the past.

As Haruto helps individuals confront and resolve their emotional burdens, he also grapples with his own fragmented memories, which hint at a deeper connection to the Tsuki Kagerō. The narrative explores the cyclical nature of time and the impact of unresolved emotions on both individuals and the world around them. Supporting characters, such as Haruto's childhood friend Yuna and a reclusive historian named Kaito, provide additional layers to the story, offering insights into the town's history and the significance of the lunar phenomenon.

The plot builds toward a climactic revelation about the true nature of the Tsuki Kagerō and its connection to Haruto and Satsuki. The series balances episodic storytelling with an overarching mystery, weaving together personal struggles and supernatural elements to create a cohesive narrative. Themes of forgiveness, acceptance, and the enduring power of memory are central to the story, culminating in a resolution that ties together the fates of the characters and the town itself.