Mitsumine Kanata is good! No pointers to give there, Stern

Oh, and Innovative, that's just how I have envisioned the ninja clans working. If I did ninja characters, they would be NPCs so certainly feel free to make your own as one of Ryuunnosuke's allies. Just take into account how the ninja clans tend to serve numerous of the ruling clans and have some degree of rivalries between themselves. Your ninja can be a protector and personal agent of the Mitsumine who offered themselves to protect Ryuu for political and monetary gain or they may have been hired some time ago by Takeshi for protection. Seeing how the uncle is very wary of outside threats, that's very likely.