Mr. Titan, also known as One-Eyed Titan or simply Titan, serves as a high-ranking executive officer within the evil organization Black Satan and is one of the primary antagonists encountered during the first half of the series. His background is rooted in his position as a senior commander of Black Satan's Japanese branch, where he operates as a direct subordinate to the mysterious Great Leader who commands the organization from behind the scenes. In his human guise, Mr. Titan adopts the appearance of a well-dressed, sophisticated gentleman who frequently wears sunglasses and smokes a cigarette, projecting an air of cool authority and mystique. This human form allows him to move undetected in society while he orchestrates the group's schemes. His true monstrous form is characterized by a single large eye, which gives him his alternate name, and his physical design reflects his connection to magma as his energy source, lending him a volcanic and fiery theme.

Personality-wise, Mr. Titan is depicted as cold, calculating, and composed, rarely displaying overt emotion even in the face of setbacks. He possesses a mystical aura that adds to his intimidating presence, and he often takes to the battlefield personally rather than relying solely on subordinates. His primary motivation is the complete destruction of Kamen Rider Stronger, whom he views as a direct threat to Black Satan's goals of world domination. This obsession drives him to extreme measures, including undergoing dangerous upgrade procedures to increase his already immense power. One such enhancement involves raising his internal body temperature to three times its normal level, a testament to his willingness to risk his own existence in pursuit of victory. The Great Leader of Black Satan imposes a conditional oath upon him: he must succeed in destroying Stronger or face death for failure, which further fuels his relentless drive.

Mr. Titan's role in the story is that of a recurring high-level threat who personally oversees the deployment of various Kikaijin, or cyborg monsters, sent to eliminate Shigeru Jo. He is directly involved in multiple early confrontations with Stronger, often leading attacks from the front lines. His significance extends beyond being a simple monster-of-the-week villain, as he survives several encounters and remains a persistent danger across multiple episodes. A key aspect of his role is his intense rivalry with General Shadow, another high-ranking Black Satan officer. The two are locked in a bitter competition for favor within the organization, and their frequent bickering and mutual distrust sometimes inadvertently allow Stronger to escape their traps. This internal friction between Titan and Shadow is a recurring subplot that highlights the fractured nature of Black Satan's leadership.

In terms of key relationships, Mr. Titan's most significant connection is with General Shadow, his direct rival within Black Satan. Their conflict is not merely professional but personal, as both seek to prove themselves superior to the other and secure the Great Leader's approval. This rivalry often puts them at odds, and Shadow eventually usurps Titan's position after his initial defeat. Mr. Titan also has a subordinate relationship with the Great Leader of Black Satan, to whom he answers directly and whose commands he must follow without question. He commands a variety of Kikaijin monsters that serve as his foot soldiers and attack units, and he is responsible for overseeing their missions against Stronger. His relationship with Shigeru Jo, Kamen Rider Stronger, is one of mutual enmity, with Titan viewing Stronger as an obstacle to be eliminated at all costs.

Mr. Titan undergoes significant development through his revival and transformation. In episode 13, he is defeated by Stronger and thrown into the sea, seemingly destroyed. However, Black Satan learns of his demise and performs a dark ritual that resurrects him into a more powerful form known as Hundred-Eyed Titan, which features multiple eyes across his body. This transformation represents an escalation of his threat level and a deepening of his obsession, as he returns with renewed fury and enhanced capabilities. His return allows him to continue his rivalry with General Shadow, though his ultimately final battle takes place at the base of an active volcano, where he emerges from a lake to demonstrate that he has been upgraded to withstand even water. He is ultimately destroyed by Stronger's Stronger Double Kick, marking the end of his arc.

Notable abilities possessed by Mr. Titan include his capacity to assume a human form for infiltration and covert operations, a trait that sets him apart from many of Black Satan's more monstrous agents. In combat, he is a formidable frontline fighter who wields several unique techniques. His signature attack is the fire orb scarf, which allows him to project flames from his scarf in an offensive manner. He also employs a revolver-type weapon called the Titan destroyer gun, which he uses to augment his ranged combat capabilities. His energy source is magma, which fuels his powers and grants him a connection to heat and fire-based attacks. After his resurrection as Hundred-Eyed Titan, his physical durability and combat prowess are significantly increased, and his obsession drives him to push his body to even greater extremes through dangerous upgrades.