A behind-the-scenes look at developers conducting intense work transforming a living beautiful girl into an onahole inside a bullet train! At their workplace is a black-haired JK, whose petite frame hides F-cup charms, making her a perfect candidate full of potential. Driven by a sense of mission upon discovering this diamond in the rough, they begin development: sucking on her lewd inverted nipples, thoroughly enjoying her voluminous, shapely ass, and progressing through advanced procedures using skilled fingers, tongues, cocks, handcuffs, and powerful aphrodisiacs. After countless creampie sessions, she eventually becomes a finely tuned, semen-squeezing onahole, moaning "I'm cumming again!" The developers proudly remark, "She's got such a lovely expression now, hasn't she?" For these men, the girl's orgasmic cries are the only reward they need—such an irresistibly captivating job that one can't help but bow in admiration.