は夏休みが待ち遠しい無邪気な小学生。
は控えめだけど頑張り屋さんの中学生。
むかしは仲良し姉妹だったふたりも、最近、心の距離がなんだか遠くて……。
ある日、風は不思議な宇宙船に出会い、魔法の力を授かる。
そして一方で流もまた、素敵な魔法の力を手にしていた。
あこがれていた大人の姿に変身する風と流。
ただし、ルールがふたつ。
「期限は1年間」、「魔法のことを誰にも 知られてはいけない」。
やがてふたりはお互いの秘密を知らぬまま、
それぞれアイドルとして活躍することに――！

Sisters Fuu and Rui used to be close, but have been a bit distant from each other recently. One day, Fuu encounters a mysterious spaceship and gains magical powers. At that same time, Rui also gains magical powers, and both transform into the adults they dream to be. The sisters' powers come with two conditions: their magic powers can only be used in one year, and no one must know about it. Unaware of each other's secrets, Fuu and Rui become active as idols.

10岁的小女孩森泽优一次机缘巧合下得到神秘力量．可以变身成为一位漂亮且拥有动听歌喉的16岁美少女小甜甜。在一次电视台的户外节目中首次演唱而一鸣惊人。于是小优以家里所卖的奶油薄饼为名，开始了偶像小甜甜的银色传说。

The Space Kittens Pozi and Nega gave little Yu a magic baton and for a year she possessed the power to transform into grown up idol singer Creamy Mami and use her magic for good. Sometimes her powers caused more problems than they solved, and though everything worked out well she finally returned the baton. Ever since, Mami has been absent from the music scene, but suddenly her return is announced in a blaze of publicity. Yu and her friends uncover a campaign by bad boy Shingo to deceive the singer's many fans.

Shingo is planning the film "A Story of Two Worlds" starring Megumi. Yuu's transformation into Creamy Mami is happening without her wanting it. She is asked to star in the film too. But the magic doesn't last...

The story follows Arion, a young man kidnapped by Hades as a child and raised to believe that his mother was blinded by Zeus and that killing the ruler of Mount Olympus will cure her.