Detective Opera Milky Holmes(2010)

Tantei Opera Milky Holmes

"Sheryl, Nero, Elly, and Cordelia are the most popular students at Holmes Detective Academy, because of the many cases they've solved with their Toys and teamwork. The students and the people of the Detective City Yokohama all look up to the members of "Milky Holmes", as they're called. But on a dark and stormy night, during a battle with their rivals "The Gentlemen Thief Empire", they lose their toys, and their fate undergoes a dramatic change..."

(Source: Crunchyroll)