Argh. The cuteness, it cuts me to the bone!
The girls are:
Sherlock Sherringford (who has pink hair and a magical winged magnifying glass, fer Pete’s sake)
Nero Yuzurizaki (and no, she ain’t chubby)
Hercule Barton (yes, a girl version of Poirot, and may God not strike us down)
Cordelia Glauca (who is pretty much totally unfeminist in char design; P.D. James is going to hurt somebody)
The villains are also cute. I don’t know who “The Rat” or “Stone River” is parodying, but “Twenty” is obviously The Man of Twenty Faces from Kogoro Akechi’s adventures. The female, blue-haired, bosom-exposing Arsene is poor Lupin’s female version. Kobayashi Opera is of course modeled after Kogorou Akechi’s adopted son Kobayashi, the head of the Boys’ Detective Club. (So he’s their kid boss.) There’s a Zenigata in this thing somewhere, according to the credits, which of course points to the real life Japanese policeman and Lupin’s cartoon nemesis, a Hasegawa named after the fictional head of the samurai police Hasegawa Heizo, and a Touyama named after another real life Japanese detective Touyama Kagemoto.
Apparently the storyline is that, in the future, everybody’s got magic and that this leads to many more master criminals and master detectives, and all of them are magical. Yeah, that’s the ticket. And the kid detective agency is their after-school job, because all of them go to school at the Holmes Detective Gakuen.
This is either going to be a laugh riot, or I’m going to want to hurt somebody. Oh, man.
Aliens in This World 
It looks cute enough to be worth the time, at least.
Maybe “Stone River” is supposed to be a take-off of Rock Hudson. Like, the Hudson River?
Maybe, but he’s not blond or anything like Rock Hudson. He looks like some martial arts fighting game character.