Tomoaki Araide

Ran and Conan's physician. In his first appearance (Manga: Chapter 234, Anime: Episode 170), he was thought to be a suitor for Ran's affections, due to overreaction by Conan. Nontheless, Dr. Araide is a very kind character and Doctor, always lending a hand whenever he is needed, including helping out in Wataru Takagi's love life. However, in a lot of appearances, it is learned that he is really Sharon Vineyard, in a disguise to track down Ai Haibara. Jodie Starling discovers this, leading to Vineyard, known as Vermouth, to stop disguising herself as Dr. Araide. Dr. Araide returns to work when he finally learns the truth about Vermouth disguising herself as him, being stunned that she mastered his mannerisms and personality perfectly.

(Source: Wikipedia)