Bela is the sole female member of the supernatural trio YOUKAI-NINGEN. Her core motivation remains consistent: a profound admiration for humanity and a persistent aspiration to become human. In the original 1968 narrative, Bela is highly emotional and short-tempered, reacting with strong prejudice against humans threatening her family. She assumes a nurturing, parental role toward the youngest member, Belo, balancing protectiveness with hostility toward human adversaries. Her unique abilities include cryokinesis (freezing targets) and resurrection.

The 2019 series reimagines Bela with significant evolution. She adopts the human alias "Annabella" to attend Saint Joseph High School in Upper Town, actively engaging in school life to assimilate. This version portrays her as expressive yet frequently wounded by the inherent differences between YOUKAI-NINGEN and humans, leading to internal conflict. She wields a whip concealed in her right arm and retains cryokinetic powers. Her original backstory involving an alchemist's wife is reassigned to a new character, Vega, focusing Bela's narrative on identity struggles and social integration.

Across all media, Bela shares consistent supernatural traits: monsterification (transforming into a monstrous form), superhuman agility, teleportation, illusions, and heightened senses. Her combat style combines physical prowess with strategic freezing abilities. A 2020 spin-off live-action film, *Yokai Ningen Bela*, further explores her character. Bela's character arc consistently emphasizes her duality—caught between her supernatural existence and human yearnings—while her interactions with Bem and Belo underscore themes of familial loyalty and the pursuit of acceptance.