Akio Kimura is a student of Shinyo Academy and a character from the story of Boogiepop and Others. He is known as a classmate of Touka Miyashita and as one of the boyfriends of Naoko Kamikishiro, alongside the younger Shirou Tanaka.

In terms of background, Akio was a normal student with a reputation as a lady killer and a player, casually dating multiple girls at the same time. His relationship with Naoko began by chance when he witnessed her failed confession to Shirou Tanaka behind the school. After being noticed by Naoko, the two began spending time together, eventually developing a unique bond where they would go on dates and share cigarettes, effectively becoming an item.

Regarding his personality, Akio appears to have a laid-back and casual demeanor. He is not particularly concerned with rules, often skipping class and smoking on school grounds. Despite his reputation for being a flirt, those who know him recognize a deeper side to his character. The only person he ever truly fell in love with was Naoko, though he did not admit this to himself until after her death. He never minded that Naoko was also in love with someone else, and he found her most beautiful not when she was acting cheerful, but when she let her real, unfiltered self show.

Akio's motivations are largely rooted in his connection to Naoko. He acts as a protector of her secrets, even when doing so comes at a great personal cost. When the school discovered signs that Naoko had invited a stranger to live on the campus, Akio took the blame to shield her. He kept his promise to her not to reveal the truth about the alien Echoes, which led to his suspension and a scandal that permanently ruined his reputation among the student body. This act of loyalty demonstrates that beneath his casual exterior, he is capable of significant sacrifice for those he cares about.

His role in the story is primarily established through flashbacks and his own perspective after the main events have concluded. Two years after graduating high school, he receives an anonymous letter stating that Naoko is dead and that he should forget about her. Unable to let go, he returns to his old school to confront the past. During this visit, he encounters Touka Miyashita, who scolds him for still playing the hero and for refusing to move on from Naoko. For a moment, Touka is replaced by Boogiepop, who tells Akio that Naoko performed her duty admirably and that he must perform his own duty to make her proud. Unlike many other characters directly involved in the supernatural conflict, Akio represents the perspective of a normal person left with only questions and lingering doubts about the extraordinary events that occurred.

Key relationships define much of his character arc. His bond with Naoko is the most significant, built on mutual understanding and a shared sense of being a mess. His encounter with Touka Miyashita serves as a catalyst for his final attempt at closure. Additionally, his relationship with Shirou Tanaka is one of complex feelings, as he often questioned what Naoko saw in the younger boy, yet he remained a confidant in their unusual romantic arrangement.

In terms of development, Akio undergoes a subtle but meaningful change. He begins as a seemingly carefree student who uses relationships as a game, but he evolves into a person haunted by a genuine, unresolved love. His journey two years later is one of attempted closure. By visiting the gym storage room where Naoko had hidden Echoes, he is finally confronted with a physical remnant of the tragedy: a mummified human hand that crumbles to dust. This moment leaves him with a profound sense of horror and no clear answers, solidifying his role as a normal person forever touched by an inexplicable event.

Notable abilities are not a characteristic of Akio Kimura. He possesses no supernatural powers or special combat skills. His significance is drawn entirely from his humanity, his emotional depth, and his role as a witness to a reality he can never fully comprehend.