Chaos Head Girls Part 1:
Rimi is a mysterious pink-haired girl that Takumi encounters at the crime scene on his way home. Rimi was wearing Suimei Academy's uniform at the time and appeared to recognize Takumi. She later claims to have known Takumi for a long time, something that only Takumi seems to be unable to remember.
Nanami is Takumi's younger sister and is a first-year Suimei Academy student. She often puts up a strong front and seems to argue with her brother whenever they meet but she is actually really concerned about him
Ayase is a third-year Suimei Academy student by day and vocalist by night. She sings for a popular indie rock band named "Phantasm" (ファンタズム, Fantazumu?). Her stage name is "FES". The lyrics in her songs appears to describe the events of the recent murders, leading the police to see her as a potential suspect. She is also the most delusional of the group, believing the gigalomaniacs are the six Dark Knights of the evil god Glajioul.