In the heart of Daitoshokan, Senri Misono, a young librarian, finds herself in a taboo embrace with her twin brother, Subaru. As they explore the forbidden, they discover a new realm of sensation, their bodies entwining in a dance of lust and love, their moans echoing through the quiet stacks. Senri, her eyes wide with desire, takes Subaru's hardness into her mouth, tasting her first man, as he gently pushes his throbbing cock into her virgin pussy, filling her completely.