Toshizou Hijikata  is the main hero in HSK. While he is de-jure the second-in-command of the Shinsengumi after Isami Kondou(the leader), he is the one who does most of the work in keeping the Shinsengumi together and in check.

Hijikata is a strict disciplinarian to his troops, hence his nickname the "Demon Vice-Commander" (鬼の副長). At the same time, he is very thoughtful and mature and puts the Shinsengumi and Isami Kondou above everything else 

 He dislikes accepting help from others and appearing weak, though he will put the survival of the Shinsengumi above things like honor. 

 He has a lot of respect for women, which is one of his reasons for being so protective of the MC. When she first encounters the Shinsengumi in Season 1, it is Hijikata who vouches for her life, arguing that if she were a threat he would deal with her. Souji Okita, who has known Hijikata since his childhood, has a habit of messing around with him, especially with his haiku books. Although Hijikata is exasperated by Okita's behavior, he sees him as a little brother and is very protective of him, to a fault.