Yamane is a ninja muglox, the younger sister of Nezumi and cousin to Yatch. She partners with Momo Umezono, a human from a wealthy background comparable to Kyle Matsutake's, and wields a bird whistle as her magical instrument.

Yamane admires Yatch and often trains alongside him in ninja activities, though her own ninja abilities exceed his in skill. During the second season, she falls victim to temporary possession by the entity Darkman. This forces her brother Nezumi to align with Darkman under the alias "Ratto" to ensure her rescue.

A distinctive characteristic is her reaction to consuming sweet foods, which induces an intoxication-like state. In this state, she wreaks significant havoc on her surroundings. Her relationship with Yatch remains an ongoing element throughout the series. Sasuke, one of Yatch's henchmen, develops a crush on Yamane.