Akira Yamaguchi is a student in the class taught by Meisuke Nueno, the titular character of the series. He is recognized as one of the most intelligent pupils in the class, though his academic brilliance is often overshadowed by other traits that define his role in the story.

Akira's personality undergoes a notable transformation as the series progresses. Initially, he is portrayed as a bright but modest and somewhat unlucky boy who tries his best yet struggles to achieve his full potential. The source of his persistent bad luck is revealed to be a near-death experience in which he traveled to the Sanzu River, a spiritual boundary between the living and the dead. There, a yokai attached to him, consistently obstructing his efforts. After Nube exorcises this spirit, Akira's fortune improves, but his character remains fairly generic for a period. Later in the series, his personality shifts dramatically. He evolves into something of a mad scientist, shedding his modest demeanor for one that is more flamboyant and enthusiastic about his work. As the class's resident inventor, he becomes deeply interested in using technology to bridge the gap between the human world and the realm of yokai, often showing off his creations in the process. This passion for invention is a core part of his identity; he builds complex gadgets from junk parts scavenged from electronics stores, though his creations are often impractical and prone to malfunction.

Akira's primary motivation stems from a genuine desire to help people and make them happy through his inventions. This drive, however, can lead him to overreach, as seen when he attempts to create a robot capable of bringing a dead pet rabbit back to life. This project, fueled by instructions from a cursed tablet, endangers his classmates and forces Nube to intervene. Within the narrative, Akira serves as a supporting student character who frequently allies with Nube and other main pupils like Hiroshi, Kyoko, Makoto, and Miki. Although his initially plain personality caused him to be somewhat sidelined in favor of more dynamic characters such as Katsuya, he remains a semi-major presence throughout the story.

His most significant relationship is with his teacher, Nube, who protects him from supernatural threats and provides guidance when his inventions go awry. Akira also interacts with the wider circle of students in the class, and episodes focusing on him often bring other less-prominent classmates into the spotlight. In terms of development, Akira's journey is one of finding his niche. He moves from being a generic unlucky student to a distinct, if eccentric, inventor whose technological flair adds a unique dynamic to the group. His notable abilities lie not in combat or spiritual power, but in his sharp intellect and his talent for engineering. He can create surprisingly advanced devices from scrap materials, even if they rarely function as intended and often have chaotic consequences.