"Hikari ~Kariya wo Tsunagu Monogatari~" is a slice-of-life anime that centers around the lives of residents in the fictional town of Kariya, focusing on their interconnected stories and the impact of a newly constructed light rail system. The narrative unfolds through multiple perspectives, highlighting the daily struggles, aspirations, and relationships of the townspeople. The light rail, named Hikari, serves as both a literal and symbolic connection between the characters, representing progress, change, and the ties that bind the community.

The story begins with the introduction of the light rail project, which sparks mixed reactions among the residents. Some view it as an opportunity for economic growth and modernization, while others fear it will disrupt the town's traditional way of life. The series delves into the lives of key characters, including a young engineer tasked with overseeing the rail's construction, a high school student grappling with her future, a shopkeeper struggling to keep his business afloat, and an elderly woman who reminisces about the town's past. Each character's journey is intricately woven into the broader narrative, showcasing how their personal challenges and triumphs are influenced by the arrival of the Hikari rail.

As the light rail becomes operational, the town undergoes gradual transformation. The series explores themes of community, resilience, and adaptation, emphasizing how the characters navigate change while preserving their connections to one another. The rail system not only facilitates physical movement but also fosters emotional and social bonds, bringing people together in unexpected ways. Through its episodic structure, the anime provides a nuanced portrayal of small-town life, capturing the quiet yet profound moments that define the human experience. The interplay between individual stories and the collective identity of Kariya creates a rich, layered narrative that resonates with themes of unity and progress.