Please note that these character descriptions will contain
spoilers.
Kamiya
Seizaborou
Once Tominaga Sei, the daughter of a
doctor, she lived a normal life until her home was attacked because her
father would treat anyone, regardless of who they supported in the growing
conflict. Her beloved older brother was also killed in the attack, and Sei
decided to fulfill her brother's dreams of joining the Shinsengumi where she
would also avenge their deaths. Although she comes into the Miburoshi not
skilled in sword fighting, Kondou and Hijikata admire her spirit (and
Serizawa thinks that "he's" cute!) and she's permitted to join. She quickly
grows close to Okita Souji, who discovers her secret but agrees to keep
quiet after hearing her story.
Okita
Souji
A prodigy in sword fighting, Okita has a
sweet, lighthearted side but when fighting his more serious side comes out.
As captain of the First Squad, Sei comes under his guidance. He seems
oblivious to Sei's feelings for him but is very protective of her, and in
the beginning even tries to get her to leave the Miburoshi. He's closest to
Hijikata and Saitou - for most of the series he and Saitou have been
roommates, but at least Saitou seems to be a deep sleeper.

Saitou Hajime
See our page here for more information on the Captain of the
Third Squad, who is, after Sei and Souji, the next major character of the
series.
Hijikata Toshizo
Okita's closest friend is the vice-commander of the
Shinsengumi, who he has known since childhood. Often seen as stern, Hijikata
is the one who has to apply the force to accomplish what is needed and to
instill discipline.
Kondou Isami
The bold and charismatic leader of the Shinsengumi, who shows
wisdom and kindness but also has a firm strength. In flashbacks to Okita's
childhood it shows that he thinks of Kondou as a father figure.

Yamanami Keisuke (Sannan)
The vice-commander is a quiet, kind man who
romances Akesato. His death by seppuku shakes the Shinsengumi.
Serizawa Kamo
A leader in the Miburoshi, he's a loud, crude man who's
often drinking and partying and pays Sei more attention than she's
comfortable with, but it hides a calculating and shrewd mind. Later, he is
assassinated, and his followers also killed or made to leave as the
Miburoshi become the Shinsengumi.

Itou Kashitarou
Joining up later on in the series as a military advisor,
he is a sly man who has an INTENSE crush on Hijikata, much to the
vice-commander's chagrin, but like Serizawa it is a cover for his more
secretive behavior.
Nagakura Shinpachi, Harada Sanosuke and Todou Heisuke - this trio is often
seen together, causing mischief but all three are strong fighters who have
been devoted to Kondou since their days at the Shieken dojo. They love to
tease Sei, esp. Harada, who seems to have a crush on "him".
Inoue Genzabarou - A frequent companion to Nagakura, Harada and Todou, he is
referred to as the oldest in the Shinsengumi but will always vigorously deny
that he's old!