温泉旅館で見つけたちっぱいお嬢さんが高額賞金目指して男湯にタオル一枚で入ってつるぺたチャレンジ！！堂々と男性のフリをして胸を隠さず！つるぺたおっぱい丸出してで男湯に突撃！！バレずに様々なミッションをクリアすれば賞金ゲット！難易度の高いエロいミッションは当然、金額もぐんぐんアップ！！男性客に話しかけてもバレないかな！？他の男性客にバレない様にこっそり手コキ！内緒でフェラチオ！？最高難易度のつるぺたセックスにチャレンジするも…バレちゃった！？興奮した男性客たちにちっぱいお嬢さんも大興奮！？さらに体を張ってみんなで仲良くエロエロ乱交までして『大量の精子採取』に成功して高額賞金ゲットなるか！？

A flat-chested girl found at a hot spring inn takes on a flat-chested challenge, entering the men's bath with only a towel on, aiming for a large cash prize! She boldly pretends to be a man and doesn't try to hide her chest! She charges into the men's bath with her flat chest completely exposed! If she completes various missions without being discovered, she wins the prize money! Naturally, the more difficult and erotic the mission, the higher the prize money! Will she be able to talk to the male guests without being discovered? She secretly gives a handjob without being noticed by the other male guests! She secretly gives a blowjob? She tries the most difficult flat-chested sex challenge, but… she gets discovered? The flat-chested girl gets very excited by the excited male guests! Will she be able to win the large cash prize by putting her body on the line and having a friendly erotic orgy with everyone, successfully collecting a large amount of sperm?