Seiichi's younger sister. Although Hotaru was only a high school student, due to Seiichi's influence, she too got inquisitive with the serial disappearance in Lovely Hills town. Similarly like her brother, she believed that Hell Hotline's existence was a urban legend, until one day she paid a visit to Takuma's house regarding Hell Hotline and she met Kikuri.

Kikuri brought to a faraway place where Hell Girl resided & showed her the candles, which on them were names of the people who requested the vengeance & the victims who were sent to Hell. Being unable to find Takuma's name on them, she believed even more that Takuma is an innocent party.