Akira Ichijō is a supporting character in the series. He is a tall, middle-aged man with short black hair and black eyes, and he works as a psychiatrist. As the husband of Reiko Ichijō, he is the father of Eiji and Karen Ichijō, and is initially presented as the head of a seemingly perfect and harmonious family. Akira carries himself with a serious demeanor and is described as a hardworking individual who believes in the harmony of his own household. He fulfills the role of the ideal father within the ideal family that his wife, Reiko, strives to maintain. Despite this outward perfection, he once sought a break from the unrelenting demands of his wife's perfectionism, which led to a romantic relationship with the family's maid, Metry. From this affair, Metry gave birth to triplets: Eiji, Migi, and Dali. Akira was unaware that Metry had become pregnant, and he never learned that the triplets were his sons or that the boy adopted by the Sonoyama family as Hitori was actually two of his children, Migi and Dali, switching places. He also remained ignorant of Metry's true fate, having assumed she simply ran away.

In the story, Akira serves as a link to the past and the central mystery, as his hidden relationship with Metry makes him the biological father of the protagonists. His role is largely defined by his ignorance of the secrets festering within his own family. He is shown to genuinely care for his known family; he expresses concern for his daughter, shows grief upon seeing his wife's body, and vigorously defends his son Eiji during his criminal investigation, trying to protect him from the consequences of his actions. His key relationships are defined by a lack of full knowledge. He is the unsuspecting father to Migi and Dali, who investigate the death of their mother Metry, and he remains unaware that Metry died rather than disappeared. When Migi, disguised as the ghost of Metry, appears before him, Akira embraces the apparition and calls out her name, revealing that he had searched for her and that he never knew she was dead. This event, along with the discovery of his affair, helps the twins deduce that he is likely their father.

Akira experiences little personal development over the course of the story, as he is never made aware of the most significant truths concerning his family, including his wife's crimes, the fate of his mistress, or the existence of his other sons. His motivations are rooted in maintaining his family and protecting his known son, Eiji. He does not possess any notable abilities that are highlighted in the narrative, with his profession as a psychiatrist being his primary characteristic. His significance lies in his role as the absent, unknowing patriarch whose past actions set the stage for the series' central conflicts.