Agent Shiro Shirota is a military officer assigned by the security forces to serve as the tactical advisor for the Dai-Guard team. He is 31 years old and a graduate of a university in London. Shirota is initially characterized by a strict, logical, and unemotional demeanor, demonstrating a firm belief in following orders, practical planning, and disciplined teamwork. He is deeply skeptical of civilians handling the Heterodyne crisis and is very insistent that the military should be in charge. This creates natural conflict with the more impulsive and justice-driven members of the Public Relations Division, particularly Shunsuke Akagi, whose improvisational style clashes with Shirota's regulation-focused approach.

Shirota's primary motivation is the effective and strategic defeat of the Heterodyne threat. His methods are informed by a tactical mindset that values insight and strategic plans, and he initially believes that casualties are an unavoidable part of such operations. However, his views undergo a significant transformation through his interactions with the civilian pilots of the Dai-Guard team. Observing their competence and the results they achieve where the military has failed forces him to re-evaluate his position. He evolves from a cold, hardline officer into one of the team's biggest supporters within the army, frequently risking his own career to assist them. This change represents a notable growth in his character, as he begins to show more humanity and adapts his tactics to fit the unique strengths and personalities of the Dai-Guard team, enabling them to fight more efficiently.

In his role as tactical advisor, Shirota is arguably the most strategically capable member of the security forces, possessing excellent insight and tactical acumen. He is a skilled pilot, capable of operating the Dai-Guard effectively when necessary, and is able to secure a license for the special vehicle quickly. Beyond his professional abilities, Shirota possesses an unexpected talent for cake decorating, a hidden depth that surprises those who know him. He demonstrates a strong capacity for concentration and efficiency, able to complete tedious tasks with perfect precision. As the story progresses, he becomes a key figure in navigating the complex intersection of military protocol, corporate politics, and the practical needs of the Dai-Guard team, even using his understanding of media to manage situations. His key relationships are central to his development, with his evolving dynamic with Akagi being particularly instrumental in changing his worldview.