The Sasaki family is as elite as it gets, and one of its members, Tetsunosuke, has joined the Shinsengumi.  He would have joined the Mimawarigumi, a police force with pedigree, but he is considered a troublemaker, which is why he was sent to the Shinsengumi.  Kondo assigns Tetsu to Hijikata as an assistant, so Hijikata is forced to endure the new recruit...
I can't let the vice chief become 
an impotent cancer-ridden murderer!
¡No dejaré que el subcomandante 
sea un asesino impotente!
Não posso deixar o tenente virar 
um agente assassino do câncer.