Hikaru Kamiki fathered Aquamarine and Ruby Hoshino. As said, Hikaru is the show’s adversary. After extensive teasing, Akane revealed Aqua, Ruby, and Taiki’s father in chapter 96 of the manga.
Hikaru also kills female idols and actresses and likes seeing them die. Kamiki approaches his victims before murdering them.
Kamiki may have secretly fathered Taiki Himekawa with Airi Himekawa, who is married. Taiki Himekawa thought his father was Seijuurou Uehara, Airi’s husband, not Hikaru.
