Kaze Hikaru Vol. 20 (manga)

Hijikata decides to make use of Kamiya's feminine features and sends "him" out dressed as a woman on a spy mission. Her assignment: to ascertain the whereabouts of the notorious enemy leader Sakamoto Ryoma. Soji, left in the dark about the secret mission, sets off to find Kamiya. The two get more than they bargained for when they come face-to-face with the enemy himself!