男水着チャレンジに挑んだあのツルペタ女子たちが今度は男湯チャレンジに挑戦！ 男装して温泉旅館にチェックイン！ プールでの失敗を生かした‘秘密兵器’を持っていざ男湯へ！ ボーイッシュ娘がタオル一枚を腰に巻き度胸試し！ 湯船にタオルを漬けちゃダメと言われて…プールの時よりヤバいかも～（汗）。過激になっていく羞恥ミッション！ 最後はまたまた女子であることがバレちゃって…！？

Those flat-chested girls who took on the men’s swimwear challenge are now tackling the men’s bath challenge! Dressed as guys, they check into a hot spring inn! Armed with a “secret weapon” inspired by their pool mishap, they head into the men’s bath! A tomboyish girl wraps a single towel around her waist to test her courage! But she’s told not to get the towel wet in the bath… This might be even riskier than the pool incident~ (sweat). The embarrassing missions are getting more and more extreme! In the end, will her true identity as a girl be exposed again…!?