Nakaoka Shintarou

A former ronin of the Tosa Domain.
Nakaoka Shintarou is a longtime associate of Sakamoto Ryouma who cooperates with the Imperial Nationalist party. He has curried high favor among the Satsuma and Choshu Domains' elite, and he hopes to help overthrow the shogunate.
In many ways, he is the polar opposite to Sakamoto.