"The Summer You Were There" centers on the relationship between two high school girls, Shizuku and Kaori, whose lives intertwine in unexpected ways. Shizuku, a reserved and introspective student, struggles with feelings of isolation and a lack of purpose. Her life takes a turn when she meets Kaori, a vibrant and outgoing classmate who seems to embody everything Shizuku is not. Despite their contrasting personalities, the two form a deep bond, with Kaori encouraging Shizuku to open up and embrace life more fully.

As their friendship deepens, it becomes clear that Kaori is harboring a secret: she is terminally ill. The narrative explores the emotional weight of this revelation, as Shizuku grapples with the impending loss of someone who has profoundly impacted her life. The story delves into themes of mortality, the fleeting nature of time, and the transformative power of human connection. Through their shared experiences, Shizuku learns to confront her own fears and insecurities, while Kaori finds solace in the moments they create together.

The manga balances moments of lightheartedness and joy with poignant, heart-wrenching scenes, capturing the bittersweet nature of their relationship. The characters are portrayed with depth and nuance, allowing their emotions and growth to resonate with readers. The narrative structure alternates between present-day events and flashbacks, providing insight into how their bond evolved over time. The story ultimately serves as a meditation on love, loss, and the enduring impact of meaningful relationships, even in the face of inevitable separation.