Jun is Ai's step-sibling; they share an apartment after moving away from their divorced parents. Their family life was cold and affectionless, marked by their father abusing Ai before his death. Jun witnessed this abuse but was unable to stop it, while their mother remained indifferent. Following their father's death, Jun and Ai strive for a quieter student existence. This stability is shattered by Tomoko and her friends, who use blackmail and violence to sexually coerce them. Tomoko's group remains unaware of Jun and Ai's past trauma and the potential reactions this history might provoke. Jun and Ai mutually cope with their shared history of sexual and emotional abuse, including nightly acts of comfort. They now navigate the lingering effects of their familial trauma alongside the ongoing exploitation by their peers.