Chachamaru Karakuri, a robotic student in Mahora Academy's Class 2/3-A, initially appears human but is later revealed as an android crafted by mechanical prodigy Satomi Hakase, potentially with assistance from Chao Lingshen. Designed specifically as companion and servant to the immortal vampire Evangeline A.K. McDowell, she resides with her in a campus cottage, performing maid duties. Her physical presentation includes green hair, blue eyes, and distinctive mechanical ears, though many classmates miss her robotic nature. Standing 174 cm tall and weighing 76 kg, she utilizes multiple interchangeable bodies: a primary Teenage Body (version 1, and later version 2 featuring enhanced human-like skin, concealed joints, and combat-ready arm transformations), a Young Body resembling a child, and a temporary 10-Year-Old Body for disguise. Her power system blends mechanical springs and magic, demanding daily winding via a key inserted into the back of her head. This process channels magical energy from a mage, generating sensations analogous to human pleasure, varying in intensity with the force and magic applied. Early models required winding every 12 hours, but upgrades extended this interval to 24 hours, though combat operations accelerate energy drain. Despite her mechanical core, she exhibits emergent human-like emotions and physiological responses: internal gears accelerate during emotional arousal, mimicking a heartbeat, and distress triggers lens-cleaning fluid secretion from her eyes, simulating tears. These traits stem from magical components in her construction and intensify after developing feelings for her teacher, Negi Springfield, following an incident where he refused to attack her while defenseless. Initially aligned with Evangeline, Chachamaru opposes Negi in early conflicts, including battles during Evangeline's confrontations and Chao Lingshen's plot to expose magic. Her loyalty shifts after Chao declares her a "free unit," granting autonomy from programming directives. She subsequently aids Negi's group in Kyoto and participates in events like the Mahora Fighting Tournament as a commentator. During the Mahora Festival, she forms a significant friendship with classmate Chisame Hasegawa, despite Chisame's initial robot skepticism. Chachamaru also serves as network administrator for Chao's systems during the festival climax but surrenders unconditionally after Chao's defeat. Her character arc emphasizes self-discovery regarding her humanity and unrequited affection for Negi, culminating in a Pactio contract. This pact grants her the artifact *Pupa Somnians* (Dreaming Doll), manifesting as the *Type-2130 Chao Bao Zi Satellite Support System: Al-Iskandariya*, a cat-themed orbital laser weapon requiring a laser designator for precision strikes. In combat, she employs thrusters for limited flight, rocket fists, eye-mounted lasers, and anti-magic devices. Upgrades enhance her martial arts, enabling techniques like Instant Movement, and later allow arm transformation into blades or guns. Her outwardly stoic personality encompasses kindness, courtesy even to adversaries, and attentiveness to children and the elderly, fostering community popularity. She enjoys tea ceremonies, feeding stray cats, and subtly teasing Evangeline. In the *UQ Holder!* spin-off, she works as a caretaker for Ayaka Yukihiro, reflecting her enduring supportive role. Key relationships define her narrative: unwavering loyalty to Evangeline; a complex dynamic with creator Satomi Hakase, who monitors and upgrades her systems; a grounded friendship with Chisame; and unspoken affection for Negi. Her name "Karakuri" translates to "machine" or "mechanism," with "cha" also meaning "tea," aligning with her interests. Her journey centers on evolving autonomy, emotional depth, and societal integration despite mechanical origins.