Atsushi Misonogi is introduced as a mysterious and affluent benefactor who financially supports Professor Horiguchi’s research into the Gransazers. His true identity and motives remain unclear in his early appearances, adding an air of intrigue to his character. He is a man of few words, carrying himself with an elegant and reserved demeanor that commands attention and respect from those who work for him.

His background is rooted in the highest levels of Japanese government and military authority. Misonogi is eventually revealed to be a high-ranking official, serving as the head of the Special Missions Division within the Ministry of Defense. This position grants him significant power, including the ability to conceal battles between the Gransazers from the public and the media. His initial goal in tracking the Gransazers is a pragmatic and nationalistic one: to use their power to strengthen Japan's military standing and make the nation a dominant global power. He approaches this objective as a consummate professional, appearing cold, calculating, and unconcerned with being seen as friendly or kind.

However, Misonogi's motivations evolve as the series progresses. When the true scale of the extraterrestrial threat becomes clear, he undergoes a significant shift in perspective. Recognizing that the invading alien fleet poses an existential danger to the entire planet, he decides to fully support the four tribes of Gransazers. While his underlying desire for strength and control does not vanish, his focus changes from national enhancement to global defense. He understands that the Sazers must be organized and monitored closely, and he orchestrates this support by forming a special operations unit known as Moonlight to assist them.

In the story, Misonogi serves as a key secondary character and an indispensable human ally. His role is to provide the Gransazers with resources, strategic direction, and a connection to the world's political and military structures. He is a constant presence in the command center, coordinating operations and making difficult decisions that the younger Sazer warriors are not equipped to handle. His key relationships are primarily professional. He is the direct superior and benefactor to Professor Horiguchi, using the professor's research for his own ends. He also commands the soldiers of the Moonlight unit, demonstrating a quiet concern for their well-being as his subordinates.

Throughout the series, Atsushi Misonogi shows notable development. He begins as an ambiguous figure whose loyalties are suspect, but he gradually proves himself to be a reliable and principled leader in the face of an alien apocalypse. While his initial actions might be interpreted as selfish, his later conduct shows that he has clear boundaries and a genuine sense of duty. He is not a warrior himself, but his authority, strategic mind, and unwavering professionalism are as critical to the Earth's defense as the Gransazers' combat abilities. His notable abilities lie not in physical combat but in his political acumen, his authority to command military resources, his capacity for strategic planning, and his ability to keep the existence of the Sazers a secret from the public, ensuring they can operate without interference.