Ken Kurenai serves as the main protagonist and pilot of the titular robot, Red Baron, in the anime. His primary motivation for participating in the Metal Fight tournament is straightforward: he aims to become its champion. He tends to act in a silly, lighthearted manner in everyday situations, but when the context demands it, he is capable of becoming serious, logical, and focused.

Ken has a secret romantic affection for his teammate, Shoko Saeba. Their first encounter was notably inauspicious; Ken initially mistook Shoko for a boy, which led her to reveal her face and subsequently kick him between the legs in the first episode. In addition to butting heads with Shoko, he also frequently clashes with their robotic companion, Robby. Ken possesses a history as a highly skilled martial artist, having trained in Muay Thai from childhood alongside his eventual rival, a character named Shadow. This shared history is the foundation of their early and intense rivalry.

In combat, Ken demonstrates great strategic ability, effectively analyzing enemy techniques to identify their weak spots. His most defining trait, however, is his indomitable will; he is never willing to give up, even when his machine sustains grievous injuries, such as having one of its arms torn off or a critical cooling device ripped from its chest. This fighting spirit is so powerful that it becomes a tangible asset, allowing him to channel his own spiritual energy to grant the Red Baron a significant power boost to win his most difficult fights.

A notable mystery surrounds his true identity. When introducing himself to the character Isao Kumano in the first episode, Ken pauses to look at a bunch of roses before saying his name. Kurenai is the Japanese word for crimson or, poetically, a rose. This, combined with the hesitation, has led to speculation that his given name might not be his real one. This is reflected in the Spanish translation of the series, where his name is rendered as Kent de la Rosa.