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ランジェリーのデザイン会社で働くはるかは「大胆になれる女性をサポート」する下着開発の担当となるが、男性経験のないはるかにとって難題であり苦戦する。そんな中、酔ったはるかのデカ尻パンティに勃起した男性社員がデカチンを絶倫挿入して…しかしその日以来、プロジェクトが順調に進み出したことで「もっとやらしいことをして下着の魅力を理解しないと」と思いSEXに耽るはるかは淫欄ボディまでも共同開発されてしまう…
Haruka works at a lingerie design company and is in charge of underwear development that “supports women who can become bold,” but for Haruka, who has no experience with men, it is a challenge and struggles. Meanwhile, a male employee who gets erect from Haruka’s big butt panties gets a huge penis inserted into her big dick…However, since that day, as the project has progressed smoothly, Haruka thinks that she has to do something more dirty and understands the appeal of her underwear, and even develops her body in lewd columns.