Gin is the 'Leader' of the Men In Black but not the Boss. It was proven correct in Volume 41 when Vermouth sent a text message to their Boss and then calling Gin and not calling him 'Boss'.
Vermouth is a part of the Men in Black. She is also the master of desquise along with Vivian Kudo , Jimmy 's mum. Her objective was to capture Sherry , but Conan made her give up on this mission on a very dagerous bet.
Burbon is a character that is one of the Men In Black . Somewhat, it seems though he hates Shuichi Akai alot throughout the story. Once, he dressed up with Vermouth, as a pregnant lady and her husband, at a place where they metConan and Jodie Starling. There was a pick-pocket murderer there and Conanhad to solve the case. Vermouth put a bug on the 'kitty '. Later in the story, Burbon, still dressed up, took the bug off and drove in a car with Vermouth .
Sherry used to be a scientist working for the Men In Black. Since they shot her sister, who used to work for the Men In Black aswell, she said she will not work anymore. Gin and Vodka handcuffed her to a wall in a cellar because of her attitude and threatened to shoot her the next morning. She had no choice but to eat the APTX4869 drug she made thinking that it is the same as being shot the next morning. Luckily, instead of dying, she turned small and her hand wriggled out of the handcuff. She soon ran to Doc Agasa's House.
Their boss. In Volume 41, Vermouth sent a text message to their boss.