Puchi Puri Yuushi

There is a legend that the gods granted the hero a task, which is to raise a little girl into something extraordinary. In this story, this young girl is Yushi, a 17-year-old girl that has been put under a spell: her body stopped aging ever since she was ten years old. She has been selected as a candidate to become the next Puchi Puri Princess. The girl selected to be princess will receive a magical tiara which grants the wearer anything she wants. This means that if Yuushi becomes princess she can wish her spell away! However, the competition is stiff and Yuushi still looks like a 10-year-old girl.
Source: Baka-Updates
Notes: This manga details the beginning journey of Yushi becoming a candidate and attending an academy where she will be trained the modesty of being a potential Puchi Puri Princess. The story is to be continued in the anime version of this title