Kaoru Akikaze is an elderly character who serves as a member of the Biology Unit within the spy organization Hinagiku. He is also known as the Master of Cafe Hinagiku, a position that blends his professional duties with a more public-facing role. His background is rooted in his affiliation with Hinagiku, where his expertise is valued enough to be called upon for specific missions, demonstrating a long-standing career in the espionage and biological sciences fields.

In terms of personality, Kaoru presents himself as a kind and perceptive individual. He demonstrates a willingness to assist others, notably helping Taiyo Asano procure a special type of tea known as Dark Sweet tea leaves. His perceptiveness is highlighted when he notices a troubled expression on Mutsumi Yozakura's face, which leads him to take the initiative to clear up a misunderstanding, suggesting a thoughtful and proactive nature that seeks to resolve interpersonal issues rather than ignore them.

Kaoru's motivations are closely tied to his duties within Hinagiku and his role as a cafe master. He appears committed to using his knowledge of plant life, a skill derived from his position in the Biology Unit, to aid in missions that require such expertise. His actions, such as helping to capture operatives from the antagonistic Tanpopo organization and assisting in freeing human experiments during the Mission: Yozakura Frontlines, show a clear dedication to the larger objectives of his organization and a sense of duty towards protecting others.

His role in the story is primarily supportive. He acts as an asset to the main characters, providing crucial assistance during specific missions. For example, his knowledge is instrumental in acquiring the Dark Sweet tea leaves. He also serves as a gateway to Hinagiku's headquarters, allowing entry to authorized individuals from his cafe. During larger-scale conflicts, he is part of the combined forces that arrive to subdue enemies, indicating that he is a reliable, if not frontline, member of the spy community.

A key relationship for Kaoru is with his granddaughter, Momiji Akikaze. They are often seen working together, both in the cafe and on missions, such as when they both assisted Taiyo. Their bond is significant enough that they act as a pair, with Kaoru involving his granddaughter in his work. He also has a professional and amicable relationship with Taiyo Asano and Mutsumi Yozakura, to the point of visiting their home to clear up a personal misunderstanding, showing that his interactions with them go beyond mere transactional exchanges.

Kaoru's development is subtle but present. While he is introduced as a helpful background figure, his involvement in the Yozakura Frontlines mission shows his willingness to participate in more direct action and large-scale operations. His consistent presence as both a knowledgeable biologist and a cafe master suggests a character who balances a quiet daily life with the serious responsibilities of a spy when the situation demands it.

Regarding his notable abilities, Kaoru possesses high-level spy capabilities consistent with being a member of Hinagiku. His specific expertise lies in his knowledge of plant life, which he uses to navigate biological challenges. This skill is directly applied when he assists in acquiring a specific type of tea leaf, an ability that proves crucial for the mission at hand. His physical appearance, always shown with his eyes closed and sporting grey hair styled upwards, a mustache, a short beard, and multiple earrings, makes him easily recognizable. He is typically seen in his white cafe uniform with a waistcoat and bowtie, though he wears a black long coat and hat when conducting business outside.