Akira Mitani is the stern and emotionally distant father of protagonist Wataru Mitani. He displays consistent disapproval toward his son's habits and behaviors, even minor ones. His relationship with his family is strained, characterized by a distinct lack of warmth and an overall detached attitude.

A significant element of his background is his decision to abandon his family. He explicitly declares his intent to leave them for another woman to Wataru, an action perceived as shocking and uncharacteristic given his known aversion to jokes and lightheartedness. This abrupt departure creates profound emotional turmoil within the Mitani household and serves as the primary catalyst for Wataru's subsequent journey.

Physically, Akira is depicted as a black-haired, grey-eyed adult male who wears glasses. He bears a resemblance to Wataru, a similarity that becomes a point of disappointment for his son. His character role and development remain consistent across adaptations, with no significant changes detailed beyond the initial abandonment.