Kaosu is a mysterious and ancient spiritual figure who serves as a guide and mentor to the five young heroes known as the Samurai Troopers. His appearance is that of a wandering monk or ascetic, traditionally depicted wearing simple robes and a distinctive cone-shaped wicker hat that often conceals his face. His long white hair, visible beneath the hat, is a notable feature, as it deviates from the shaved heads commonly associated with Buddhist monks. He carries a shakujo, a ringed tin staff traditionally used by mendicant monks, which accompanies him on his journeys.

The background of Kaosu is deeply rooted in the ancient struggle against the demonic overlord Arago. Approximately one thousand years before the main events of the story, Kaosu confronted Arago, who was attempting to conquer the human world. In a decisive battle, Kaosu managed to defeat the demon and banish him back to his own realm. However, he could not destroy Arago's malevolent armor. To prevent the demon from easily returning to power, Kaosu used his mystical abilities to reforge the single dark armor into nine separate sets of mystical armor. Each of these suits was imbued with a specific human virtue, such as righteousness or wisdom, intended to help the wearer resist the armor's lingering evil and corruption. While five of these armors eventually found their way to the five protagonists, the other four were corrupted by Arago and became the dark armors of his four demon generals.

In the present day, Kaosu exists more as a spirit than a fully physical being, having used his considerable magical powers to remain manifested in anticipation of Arago's return. His primary motivation is to ensure the forces of light prevail over the demon world. He is dedicated to guiding the young warriors who now possess the armors, helping them to master their powers and fulfill their destiny as the Samurai Troopers. He believes the warriors’ pure hearts and the virtues instilled in their armors are the keys to finally destroying Arago for good.

Kaosu’s role in the story is that of a wise, behind-the-scenes mentor and the strategic architect of the heroes’ quest. He does not fight the battles for the Troopers but instead appears at crucial moments to provide them with guidance, mystical aid, or a path forward. He has a deep connection to the white tiger Byakuen, who often serves as his envoy and leads the Troopers to him. As Arago’s ancient counterpart and sworn enemy, Kaosu is the demon’s primary target. In a pivotal moment, Kaosu is seemingly defeated and absorbed by Arago. Even in this apparent defeat, he performs perhaps his most significant act of guidance, using his remaining energy to create a bridge from Arago’s floating fortress back to Tokyo, giving the Troopers the opening they need to launch their final assault. This self-sacrifice demonstrates his complete commitment to his cause.

The development of Kaosu is largely static, as he already possesses the wisdom and power of a legendary figure. His evolution is expressed through his willingness to entrust the future to the next generation, culminating in his self-sacrifice. His legacy is not just the armors he created, but the spiritual and moral framework he provides for the young warriors, shaping them into true heroes.

Kaosu’s abilities are formidable and steeped in mysticism. As a master of both Shinto and Buddhist concepts, his powers include magic chants, creating powerful energy barriers, and firing devastating energy blasts. His shakujo is not merely a walking stick but a repository of immense magical energy, originally forged from the very sword he used to defeat Arago a millennium ago. The staff represents his transformation from a warrior into a spiritual guide. The full extent of his power is never fully revealed, maintaining an air of mystery around him. His knowledge is vast, able to sense the resurrection of Arago across dimensions and understand the complex history of the armors he created.