Ran-Mao, a Chinese woman known as Lau’s adopted younger sister, shares a childhood-forged bond with him, marked by her clingy demeanor—perching on his lap or clutching his arm—which he dismisses as that of a “pampered child.” Rarely speaking beyond terse, broken English, she maintains an expressionless facade. Her attire blends a lavender-and-black cheongsam with a dark blue cropped jacket, complemented by gold bell-adorned anklets and twin hair buns resembling feline ears, aligning with her nickname “Blue Cat,” drawn from her name’s Chinese and Japanese roots. Petite yet formidable, she wields twin chuí—heavy metal maces—to pulverize concrete and adversaries, executing Lau’s orders as his personal assassin. Her lethal precision fells targets like Harold West Jeb and Mina, yet she sporadically shields Ciel Phantomhive, hugging him post a snake rescue or posing as his decoy. Loyalty drives her to enable Lau’s ploys, from seducing Georg von Siemens and Baldroy to flaunting her legs as a cricket-match distraction. Opium consumption grants her sedative immunity, while fragmented flashbacks imply a lifelong tie to Lau. Later arcs depict her aiding Ciel’s household by demolishing sewer tunnels to evade authorities and probing the Aurora Society with Mey-Rin. A non-canon skirmish with Sebastian Michaelis highlights her protective instincts toward Lau, though their canonical dealings remain detached. Taciturn and lethally efficient, she operates as Lau’s unwavering enforcer, her actions echoing loyalty over words.