Leina Stol hails from the mechanical world of Cronos as a member of the humanoid sentient robot Cronos Tribe. She is the daughter of tribal chief Kirai Stol and younger sister to Rom Stol and Guardi Stol. Trained by her father alongside Rom, Blue Jet, Rod Drill, and Bug Newman in the martial art Tenkū Chūshin Ken (Sky Space Heart Fist), she possesses combat skills effective when needed, though her capabilities vary across storylines.

Leina shares a notably close bond with Rom, frequently displaying protectiveness and jealousy towards other women interacting with him, a dynamic persisting throughout their adventures. Her personality blends combat readiness with emotional vulnerability, especially concerning family. After Gyandlar invaders kill Kirai Stol in the series' first episode, Leina joins Rom's quest to protect Cronos and prevent the Gyandlar from obtaining the mythical Hyribead energy source.

Her journey extends into OVAs following the main series. After the events of "Machine Robo: Revenge of Cronos," Leina and Rom cross a dimensional barrier that transforms them from robots into humans and separates them. Reincarnated as Japanese schoolgirl Leina Haruka with only fragmented memories of her past, she actively searches across dimensions for her missing brother and allies. Throughout the OVA series "Leina: Wolf Sword Legend," she gradually reunites with other core characters—including Rod Drill, Blue Jet, and Triple Jim—who have also taken human forms. A significant revelation in these OVAs discloses that Leina and Rom are not blood-related siblings, complicating their relationship.

Leina represents one of the franchise's primary female figures. Her design and narrative role reflect "Action Girl" archetype elements, with combat effectiveness varying by storyline. Her transition from a robotic warrior on Cronos to a human protagonist navigating dimensional conflicts marks her evolution across official media.