Nazotoki-hime wa Meitantei♥
Genres: Mystery
Type: OVA, Episodes: 6
Aired: Aug 3, 2012 to Dec 27, 2013
Studio: SynergySP
Source: Manga
Rating: G - All Ages
Synopsis:
The story centers around Hinami, a bookish, eyeglasses-wearing girl, and her two friends. When there is a mystery to solve, she transforms into the clever Nazotoki-hime (literally, Princess Mystery Time). 

(Source: ANN)