Miki Hosokawa, a student in class 5-3, thrives as a gossip-driven troublemaker with a fascination for the supernatural. Her neck-length blonde hair, styled with bangs and a black headband, complements her blue eyes and notably curvaceous figure—a feature fueling her vanity as her bust size grows from a B-cup to an F-cup. A near-fatal encounter with a deceitful tattletale yōkai, which falsely accuses her of spreading harmful rumors, forces her to curb gossiping and deepen her study of spirits. This shift establishes her as her teacher’s occult consultant.

Her spiritual exploration awakens the rokurokubi ability, letting her stretch her neck and head covertly. Unaware the power is visible, she misuses it for cheating and pranks until her teacher temporarily seals it. The ability resurfaces in Volume 14 under her conscious control, enabling targeted espionage and pranks, particularly against Ms. Ritsuko Takahashi.

Miki’s rivalry with Kyōko Inaba revolves around physical comparisons, while her friendship with Hiroshi Tateno blends pranks and charm. She collaborates with classmates Izuna Hazuki and Shuichi Shirato, leveraging occult knowledge for schemes. The third movie briefly ignites jealousy toward Noriko Nakajima, though their dynamic remains neutral.

Her name, derived from “beautiful tree” (美樹) and “fine river” (細川), reflects her layered persona. The catchphrase “Unbelievable!” punctuates her reactions. Evolving from a comedic instigator to a spiritually attuned figure, she balances vanity and mischief with a growing mastery of the supernatural world.