Seiun Sky presents an easygoing facade, living life at her own relaxed pace and often seeming lazy. This deliberate demeanor masks her true nature as a careful observer and schemer, lulling others into lowering their guard. Her preference for a slow, deliberate lifestyle manifests in hobbies like taking afternoon naps and fishing. She's frequently seen resting outdoors with cats, displaying a distinct fondness for them. Physically, she has short powder green hair, a sunflower hair-pin clipped on her left bangs, and blue eyes that often look weary. Her right ear features a green cover decorated with cloud patterns and cotton puff details. Her typical outfit includes a basic white blouse with green accents and ruffled details, paired with green shorts displaying cloud motifs. A brown choker with a horseshoe design and gray heels featuring cloud-like embellishments complete her sky and cloud-themed look. She was classmates with Special Week and resides in the Miho dormitory alongside her roommate, Sakura Laurel. A close friendship exists with Nishino Flower, stemming from their shared ownership under Masayuki Nishiyama in real life. This bond is reflected in her giving Flower a daisy wreath; their connection extended beyond racing, as they were buried next to each other. She also interacts with peers like King Halo and Special Week as both rivals and friends. Inspired by the real thoroughbred Seiun Sky, a frontrunner known for unconventional pacing, her character is portrayed as a "trickster" in racing contexts. She employs strategic speed variations—starting fast, slowing mid-race, and accelerating late—to unsettle opponents. A recurring weakness is her aversion to confined spaces, particularly starting gates. Her career targeted major races like the Satsuki Sho, Kikka Sho, and Arima Kinen, with development emphasizing balancing her laid-back exterior with a competitive drive. Unused backstory concepts from an unreleased novel depicted her joining the rigorous training team Albireo under coercive circumstances, contrasting her free-spirited nature. This version explored her frustration after losses and a subsequent move to the strategy-focused Team Deneb, highlighting tactical adaptability. These elements were not incorporated into mainstream adaptations. Her game support card, "Foolproof Plan," emphasizes stamina and mood management, offering skills like "Escape Artist" and "Trick (Front)" that align with her frontrunning style. Event scenarios, such as "Be Strategic ☆" and "Cloudy Skies Later...," explore her interactions and choices, including skipping ceremonies or navigating team dynamics. She fishes with her grandfather during visits home; her phone background shows them reeling in a large catch. She adheres to personal rules like finishing all food and avoiding spicy dishes or tight neckwear. Her racing commentary references clear skies, nodding to her 1998 Kikka Sho victory under sunny conditions. In broader media, she appeared in a childhood flashback alongside Grass Wonder during Team Sirius' formation arc. Plans for a manga focusing on her within the "Golden Generation" were considered but canceled.