Chisato Arimiya is a central figure in the narrative, a young adult woman with wavy orange hair reaching the middle of her back and brown eyes. Her name translates to "thousand miles" or "long distance." She is the second stepdaughter of the late Kamoshige Arimiya and the biological sister of Misora Arimiya. Her immediate family consists of her deceased stepfather Kamoshige, her stepmother Sumire Arimiya, and her stepsisters Misora and Shion Arimiya.

Her background is marked by trauma, specifically sexual abuse at the hands of her stepfather, Kamoshige, resulting in a profound aversion to men. This history informs her sexual orientation as a lesbian, a fact she attempts to conceal from others. Following Kamoshige's death, Chisato was the first heiress of the family, which becomes entangled in a conflict over his hidden inheritance.

Initially, Chisato exhibits a dominant, manipulative, and cruel personality. She openly insults her stepsister Shion, belittling her status, and engages in coercive sexual relationships, forcing the family maid, Emiri Kasai, to perform oral sex on her. She is also shown torturing Shion in a secret room.

Her character undergoes significant development after the intervention of Tatsuya Katori, a young man seeking revenge on the family. Tatsuya defends Shion from her harassment and later uncovers the truth of her past abuse. This knowledge allows him to manipulate and ultimately dominate her, causing her role to shift from a dominant aggressor to becoming Tatsuya Katori's sex slave, a complete reversal in her power dynamics.