Koroku is Hiyoshi's subordinate
(Hiyoshi is here:
http://www.furaffinity.net/view/457025/
)

MoMo make Koroku and Hiyoshi as a couple. In real history, Masakatsu(Koroku) prefered staying with Hideyoshi(Hiyoshi) than other rewards. In that time, homosexual was very comment, so I believe they were that kind of relationship, too.

In my design, Koroku uses the similar fighting style as Guile in Street Fighter 2.