暮主 水晶

Name: Mizuki Kuranushi
Sex: Female
Age: 18 (Past) | 24 (Present)
Birthday: August 10
Profession: ABIS Undercover Special Agent
Likes: Mizuki Date
Dislikes: Anyone Who Messes With Mizuki Date
Hobbies: Watching Over Mizuki Date
Skills: Guessing Which Panties Mizuki Date Is Wearing That Day

Mizuki Date was born from her DNA, almost like a little sister. She lived at Aioen until she was 9 years old. Mizuki Kuranushi secretly watched over Mizuki Date from afar, watching her grow up.

Bibi was originally taken in by the Chieda Family, becoming Kizuna's "Big Sis". She was adopted at 15 by Shizue "Boss" Kuranushi, then trained and admitted into ABIS at 18. She previously worked as a thief for the Kumakura Family, going by the codename "Quartz" and assisted by Lien.
Bibi is the protagonist during "Mizuki Chapter 2" and "Mizuki Chapter 4", both set in the Past, where she is 18 years old and looks the same as 18-year-old Mizuki Date in the Present. She is accompanied by Aiba in the Past and by Marco in the Present.