Yayoi Kuribayashi is the brunette assistant of Mouse in the series.

An incredibly busty but skilled biology expert who also works as the school's nurse. Yet her clinging curiosity was noticed by her classmate, Mei Momozono, even further her in an intimate relationship with a student she was tutoring, Sorata Muon. She’s also Zach Kakio’s aunt but she always treated him like her own son.