"Pure Love" centers on the life of Yuto, a high school student who experiences a profound transformation after a tragic accident leaves him in a coma. Upon awakening, Yuto discovers he has gained the ability to see the "remaining lifespan" of those around him, represented by a countdown above their heads. This newfound ability forces him to confront the fragility of life and the inevitability of death, shaping his interactions with others in unexpected ways.

The narrative explores Yuto's relationships with his classmates, particularly Akari, a cheerful and optimistic girl who hides her own struggles behind a bright smile. Akari's countdown is alarmingly short, and Yuto becomes determined to make the most of the time they have left together. As their bond deepens, Yuto learns to appreciate the present moment and the importance of cherishing every connection, no matter how fleeting.

Throughout the series, Yuto encounters various individuals whose lifespans are nearing their end, each with their own stories and regrets. These encounters serve as poignant reminders of the value of life and the impact one can have on others. The story also delves into Yuto's internal conflict as he grapples with the moral implications of his ability—whether to intervene in the lives of those he meets or to accept the natural course of events.

Themes of love, loss, and the passage of time are woven into the narrative, creating a bittersweet tone that resonates with viewers. The series balances moments of heartfelt emotion with introspective reflections on mortality, offering a thought-provoking exploration of human relationships and the choices that define them. The characters' growth and the evolving dynamics between them drive the story forward, culminating in a conclusion that underscores the enduring power of love and memory.