Kirai Stol ruled as chief of the Cronos tribe on the mechanical planet Cronos. A master of the martial art Tenkū Chūshin Ken (Sky Space Heart Fist), he imparted its techniques to his children—Guardi, Rom, and Leina Stol—and disciples like Blue Jet, Rod Drill, and Bug Newman. His leadership and combat skill positioned him as guardian of Cronos's mythical energy source, the Hyribead.

When the Gyandlar forces attacked Cronos seeking the Hyribead, Kirai Stol refused to reveal its location, an act of defiance that cost him his life in the series' first episode. With his final breath, he entrusted his son Rom with the Wolf Sword Kenrō, commanding him to protect Cronos and fight the Gyandlar. This act ignited the series' central conflict, passing the mission to Rom and Leina.

Kirai Stol's legacy endured through his teachings. His mastery of Tenkū Chūshin Ken became the bedrock of the protagonists' fighting prowess, enabling Rom's transformations using the Kenrō sword to merge with the mighty mecha Kenryū and Baikanfū. His values of resistance and sacrifice resonated in his children's ongoing struggle, cementing his role as an enduring symbol of Cronos's defiance.