Nazotoki-hime wa Meitantei♥

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: Anime News Network)

Note: The episodes were included in "Ciao Ciao TV! (ちゃおちゃおTV!)", a bonus DVD bundled in select issues of the shoujo magazine Ciao.