Koperu-kun is a junior high school student and experiences many different things in his school. He often is given advice from his uncle about life and how to be a good person. A good portion of the book is written in the form of notebook entries and reads vertically like a novel. Most of the book is in manga form.

From Penguin Press: The streets of Tokyo swarm below fifteen-year-old Copper as he gazes out into the city of his childhood. Struck by the thought of the infinite people whose lives play out alongside his own, he begins to wonder, how do you live? Considering life's biggest questions for the first time, Copper turns to his dear uncle for heart-warming wisdom. As the old man guides the boy on a journey of philosophical discovery, a timeless tale unfolds, offering a poignant reflection on what it means to be human.