Kirameki Mikawa is Fumika Mikawa's father, a poet and artist living in an architecturally distinctive home. His eccentric behavior centers on an obsession with beauty and sparkling things, reflecting his name's meaning ("sparkle" or "shimmer"). He possesses distinctive white hair, contributing to his image as a white-haired pretty boy.

Kirameki's relationship with his daughter involved severe abuse. After Fumika's mother abandoned them—having only sought the experiences of marriage and childbirth—Kirameki initially acted as a single father. His parenting deteriorated when he began using Fumika as a literal canvas for his artistic drafts, carving his writings into her skin with glass pens and inflicting physical and psychological trauma. This abuse caused Fumika to develop dissociative identity disorder, splitting her personality into "Fumi" (a gentle identity) and "Mika" (a protective, aggressive identity).

The abuse culminated when Mika, confronting Kirameki's attempt to extend his exploitation, shot him with a handgun. This event left Fumika comatose, with Mika's consciousness becoming a shigofumi mail carrier while Fumi remained hospitalized. Years later, Kirameki received a shigofumi from a deceased fan. During its delivery, Fumika (as Mika) confronted him, wielding the same gun to force him to confront his past. When Kaname Nojima—a classmate of Fumika's—intervened, causing the gun to drop, Kirameki seized it and shot Fumika.

Subdued and locked in a room by Kaname, Kirameki escaped by extracting gunpowder from bullets to create an explosive. He then attempted to kill Fumika again but was physically restrained by his editor, Haruna Kasai. His actions define him as a Mad Artist whose pursuit of artistic perfection and beauty masked profound cruelty and parental failure, directly causing the narrative's central trauma.