Framed for business embezzlement, Hina Saotome is sentenced to one year in the notorious all-male Kokuyoku Prison. There, she encounters the elegant but merciless Warden Aki Myojin, who claims her as his personal pet and begins a campaign of "sweet punishment" — intense physical inspections, humiliating public torments, and erotic dominance that blur the line between punishment and pleasure.

While Hina clings to her innocence and her boyfriend Kiyonori Yakumo's support during visits, she is drawn deeper into Myojin's web. Fellow inmate Yamato Higa offers genuine kindness and protection, creating a complex love triangle amid prison intrigue, escape plots, gang rivalries, and dark secrets from Myojin's past.

As Hina's body betrays her with growing addiction to Myojin's touch, she faces escalating "pleasure punishments," betrayals, reversals of power, and shocking revelations about the conspiracy that landed her in prison. The story builds to a climactic confrontation where Hina must decide her fate: escape, submission, or a path toward truth and redemption. Blending intense eroticism with dramatic prison thriller elements, this hentai ONA explores themes of control, desire, innocence, and twisted affection in a high-stakes setting.