Juunikyuu de Tsukamaete

Lili is just like any other girl except she can foretell the future! This 'Zodiac PI' relies on horoscopes and astrology to help her solve crimes and track down criminals. When there's trouble a'brewing, she transforms herself into the magic Detective Spica and looks to the stars to guide her way. Before long, she is joined by her childhood friend, Hiromi, who dreams of becoming a detective as skilled as Lili. Soon, no astral investigation is too arduous for this dynamic duo!
(Source: Tokyopop)
Note: Includes four extras chapters