S1·E5 A Beauty To Be Reckoned With - Her Name is Aoi

Bukotou station receives a new officer, Aoi Futaba, who turns out to be an undercover guy who's worked so long as a gal that he's a transvestite now, and a very pretty one at that. The entire station, except for the Chief, is uncomfortable with her presence, but the gang get to see Aoi's true colors when Aoi's old girlfriend arrives asking for help, not knowing who Aoi is.