Akira Tounome is the protagonist of the story and the owner of the Tounome Detective Agency. He is an invisible man, a being whose body cannot be seen by the naked eye, though he can choose to make his clothes visible or disappear as well. His surname is a play on the Japanese word for invisible, toumei. As a child, Akira experienced a traumatic incident during a school camping trip when he became lost in a forest at night; the fact that none of his classmates noticed he was missing or came to look for him left a deep emotional scar, and he has since developed a fear of darkness.

Akira is characterized as a kind, polite, and gentlemanly individual who treats everyone with respect and affability. As a boss, he is benevolent, maintaining friendly relationships with his employees and organizing group activities such as camping trips. Despite his generally composed and respectable demeanor, he is not immune to embarrassment and can find himself flustered in awkward or intimate situations. He holds the unusual personal belief that being shirtless is just as embarrassing as being fully naked, as he feels it exposes the invisible interior of his clothing, though others do not share this view. Because his face is impossible to read, he has learned to express himself through his tone of voice and his choice of fashionable clothing.

Akira works as a private detective, a profession for which his invisibility is exceptionally well-suited, allowing him to conduct surveillance and investigations without being noticed. He takes an interest in Shizuka Yakou, a blind woman who works as the receptionist at his agency, and asks her to date him. His primary motivation stems from the unique connection he feels with her: as the only person who cannot see him, Shizuka is also the only one who can always sense his presence through her heightened hearing and touch, effectively making her the one person who can always find him. This dynamic draws him to her, as she provides a form of recognition and acceptance that transcends his physical invisibility.

Within the story, Akira serves as the central figure whose abilities and personal challenges drive the romantic narrative. His invisibility, typically a professional strength, becomes a personal drawback that shapes his insecurities about being overlooked or unnoticed, a fear that his relationship with Shizuka gradually helps to heal. He navigates the early stages of romance with a mix of earnest determination and charming awkwardness, often using his skills to create opportunities to spend time with her. His key relationships include his bond with Shizuka, his supportive interactions with his other employees such as the beastwoman Luna and the human Daichi, who offer him advice on both detective work and love.

Notable abilities include his power of invisibility, which he can switch on and off, allowing him to be either fully transparent or to have his clothing appear to float unaided. This power makes him a highly effective detective, enabling him to observe suspects and gather information undetected. He also possesses a well-built physique, though this is usually concealed by his suits and only becomes apparent under specific circumstances, such as when his shirt becomes wet. His character develops as he learns to navigate a romantic relationship, overcoming his trauma of being unseen by forming a deep connection with Shizuka, who sees him for who he is in a way that does not rely on sight.