Chamo, alias Albert Chamomile, is a talking ermine serving as Negi Springfield's familiar. Once a human wizard, he was transformed into an ermine as punishment for stealing over 3,000 pairs of girls' underwear. He escaped legal consequences by seeking refuge with Negi, claiming the boy freed him from a trap years prior. His core motivation involves brokering probationary contracts (pactio) between Negi and female students, earning 50,000 "Ermine Dollars" per contract.

Chamo displays a profoundly perverted nature, habitually pilfering lingerie and engineering pactio opportunities through schemes like rigging a kissing game’s magic circle. These antics routinely provoke violent retaliation from Asuna Kagurazaka. Despite self-serving impulses, he exhibits authentic concern for Negi’s welfare and advises him on magical affairs. His expertise covers spellcasting, anti-telepathy wards, and pactio mechanics, though his counsel occasionally proves unreliable.

In the *Spring OVA*, he materializes during Asuna’s attack on Negi after a magical mishap disrobes her, observing the clash before retreating. His role remains minimal, largely witnessing the class trip where Negi and Asuna reconcile. Across other media, his character adapts: *Negima!?* portrays him as less overtly perverse yet still incurring Asuna’s fury. In the sequel *UQ Holder!*, he appears elderly but retains underwear-thieving tendencies while recounting alternate timelines of Negi and Asuna. He also judges events like the Miss Mahora championship.

Magically, he specializes in crafting pactio circles and deploys tactics like the "Ermine Flash," merging flash bangs with his lighter for diversions. He addresses Negi as "Aniki" (big brother) and females as "Ane-san" (big sister), reflecting his familiar bond despite implied age.