The Genius Four (ジーニアスフォー), or G4 for short, is the anti-phantom thief division from Yokohama. The police department established the unite to handle all Gentlemen Thieves related incidents as they continue to increase. Whilst the members don't possess any Toys, they have their respective capabilities making them the third faction in the Milky Holmes anime.
Depicted as the series' flatfoot, they continue to stop the Phantom Thief Empire's crime spree but always end up failing while clashing with Milky Holmes after they lost their Toys.
In Futari wa Milky Holmes, they were assisting other police departments with paperwork with the lack of Gentlemen Thieves incidents happening.