Yukke, aged 14, serves as Kuppa's older sister and fellow treasure hunter in a harsh desert landscape where water scarcity has made it exceptionally precious. Her advanced engineering expertise allows her to restore and maintain salvaged robots from ruins for functional purposes. Pragmatic and thrifty, especially regarding resources like water for their robot companion Dram, Yukke contrasts sharply with Kuppa's adventurous impulsiveness. She consistently voices concern over his reckless behavior, deeming it irresponsible. Unbeknownst to her during their encounters, Yukke develops romantic feelings for Samgetan—a mysterious figure who manipulates the Aqua Luna gem and has observed human history across 3,500 years—while remaining unaware of his true nature or extended lifespan.