How about a blissful moment where Saki Sasaki, who loves her older brother so much, becomes your very own younger sister? Not only will she cheer you on, but she also comes with a special service just for you, older brother. Saying "I want to make you even more energetic" is forbidden, right~. Will they cross the line between siblings? Why not let your heart race at the forbidden relationship with kind-hearted Saki-chan?