CANON HISTORY:Kaze Hikaru on wikipedia; Sei Tominaga on the Kaze Hikaru wiki. Neither article is very detailed past what you'd read on the back of the first volume (except for the wikia article which talks about some things from before Sei was born), so I'll make an attempt at briefly summarizing what has happened to Sei up until her canon point. Feel free to ignore it if you feel the links give you enough to work with!
Sei's father, who was a western-style doctor from Edo who moved to Kyoto five years previously, and her older brother are killed by samurai from the Choshu clan; she survives thanks to intervention by Souji Okita, who has recently arrived in Kyoto along with the others who will become members of the Mibu Roshigumi. The Choshu set fire to the house and Sei suffers burns, but lives and swears revenge. In 1863, she disguises herself as a boy - going so far as to shave her head into a masculine hairstyle - and attempts to enlist in the Mibu Roshigumi under the name of Seizaburo Kamiya (Kamiya being her mother's maiden name; Seizaburo being a boyish version of her name used as a nickname for her by her older brother). Though she possesses little in terms of technique, she catches the eye of Okita and Toshizo Hijikata because of how light she is on her feet (as she manages not to dodge every strike thrown her way until she faces off against Heisuke Toudou). After it is revealed that "he" is only fifteen, a combination of approval from Kamo Serizawa and her own quick talking prompts Hijikata to allow Seizaburo Kamiya to join the troop. Sei, as Seizaburo, intends to use her membership with the Roshigumi as a way to take her revenge against the men who killed her father, as they were bound to come across the Choshu at some point in the course of their duties.
However, after her first night with them, she is disillusioned by how some of the men (cough, Harada, cough, Serizawa, cough, Nagakura...) act when not on active duty, and she attempts to escape. While doing this she runs into a spy from Choshu who was also attempting to escape, but the pair of them are discovered by Okita, who kills the spy; Sei realizes that much of the behavior she found so distasteful was an act to catch the spy off-guard, but because she is fucking stubborn had committed to leaving, attempts to fight Okita and escape. Of course she fails, but their fight is cut short when Okita accidentally cuts open her top and realizes she's a girl because her crossdressing was convincing enough for everyone to believe it until they saw boob, take notes, Chizuru Yukimura. After hearing her out, Okita decides that he will overlook the fact that she is a girl, because "no girl would go so far as to shave her head for revenge" - his way of saying that he will accept her as a man and allow her to continue with the troop if she so wishes. And so Sei casts her lot with the Mibu Roshigumi.
She begins to get to know the members of the Mibu Roshigumi and meets Hajime Saitou, who in addition to being a friend of her brother Yuuma's, also bears a striking resemblance to him in terms of appearance, voice, and mannerisms - to the point that she initially mistakes him for her brother even though he is dead. She becomes acquainted with the day-to-day workings of the troop and works to hone her skills, often discovering that she still has quite a bit to learn, not just in terms of swordsmanship but also in terms of how the world works and why her comrades live the way they do. She also meets Akesato, who now works as a prostitute in Shimabara but was once called Satono and once was involved with Sei's brother, Yuuma.
Serizawa believes that "Seizaburo" has fallen in love with Akesato, and to help him "be a man" insists that "he" come along to Osaka while investigating rumors that people are using the Mibu Roshigumi's name to extort money from merchants, so that Serizawa can take "him" along to the red-light district in Osaka and help "him" get more experience. The experience Sei gets is not what is expected - in Osaka she encounters the man who was responsible for the deaths of her father and her brother, and has the chance to take her revenge. However, because she has learned that he has a wife and a child on the way, she allows him to live but says that he must repent and support his family - though he kills himself instead for the sake of his samurai honor. After this, she tries to leave the Roshigumi (...again) but after speaking to Saitou, she realizes that she wants to protect Okita (Sei you sweet summer child he doesn't need your protection) and decides to return to Kyoto with them.
It is not too long after this incident that Serizawa meets a woman named Oume, and while watching him struggle to come to grips with his feelings for her, Sei starts to really respect Serizawa for the first time. Unfortunately, his extravagances continue after Oume comes to live with him, and after the Mibu Roshigumi is given the name "Shinsengumi," the order to assassinate him - in order to protect the good name of the Aizu clan and the shogunate - is given. Sei is initially unaware of this order, but discovers it (and that Okita played a part in it) after encountering Okita on his way back from the assassination. This time, she does not try and run away from the Shinsengumi, but tries to figure out what it means to be a true bushi. Not too long after this, she is faced with a dilemma when one of the other troop members is sentenced to seppuku and attempts to escape; she almost lets him go, but catches up with him and executes him for violating the bushido.
There are a lot of things that happen from there, and Sei learns many lessons from various members of the Shinsengumi - most often from Okita and Saitou. The next major historical event that Sei is involved with is the Ikedaya affair, during which Okita is felled and Sei, in a blind rage, blocks a strike with her hachigane before killing some of the other combatants. After this, she is instructed to take Okita back to headquarters and she stays there until he wakes up, at which point she returns to the Ikedaya to help with the rest of the raid.
(...brief, I said, and we haven't even gotten to the end of volume six yet I am so sorry. I'm going to summarize like crazy starting from now because no one wants to read this much and should you need clarification or expansion on anything I can definitely do that.)
As time goes on, Yamanami becomes involved with Akesato, who has been helping Sei keep up with her disguise by allowing her to visit on a "three-day indulgence" once a month to hide her period from the men in the Shinsengumi. Yamanami, being honest, can't bring himself to go around seeing "Seizaburo Kamiya's lover" behind his back, and to try and keep him from confronting Sei, Akesato tells Yamanami that "Seizaburo" is actually a girl. Of course, Yamanami freaks the fuck out, but Akesato convinces him to keep it a secret; he does insist on having Sei wear chainmail under her uniform as extra protection, but this works to Sei's advantage because it helps to hide her feminine figure. There is also a reorganization of the troop and Sei becomes Yamanami's page (look okay now all we need is for another crossdresser to become Kondou's page and she, Chizuru, and Sei can be a matched set).
A man named Kashitarou Itou joins the Shinsengumi to varying reactions from the men. Sei is not overly fond of him, as he is far too touchy-feely for her liking, and she, Okita, and Yamanami devise ways to keep Sei out of his reach. There is a fiasco where Itou is to move into Yamanami's room, but at the last minute Hijikata transfers Sei into the first troop, to be under Okita's direct command. At that point Yamanami and Itou begin to room together and Yamanami becomes caught between a rock and a hard place when Kondou and Itou both try to get him to convince the other that their views are the correct ones.
This situation escalates when a friend of Itou's is executed and Itou blames the shogunate for it. Yamanami, who at this point has begun to see some of the points Itou is trying to make, realizes that he cannot change Kondou's mind and instead chooses to leave the troop, give Akesato's family the money to free her from her servitude in Shimabara, and then allows Okita to bring him back to commit seppuku. Sei is devastated by this, as she and Yamanami had grown incredibly close.
Not long after this, the Shinsengumi's headquarters moves to the Nishi Honganji temple. Sei, who is starting to look more and more womanly as she gets older, struggles to keep her gender a secret; she finds help in the form of Ryojun Matsumoto, a doctor who had been a friend of her father's. When he comes to do an medical inspection of the Shinsengumi, he tells everyone that "Seizaburo Kamiya" is suffering from a rare disease called feminitis, which changes a man's body into that of a woman's. Between his word and the fact that he cited "western research" (which was really just him making things up), everyone comes to believe it because none of them would ever expect a respected physician to lie for the sake of a girl.
With her position in the Shinsengumi secure, Sei goes about her life as a member of the troop. She trains, she goes to Osaka to help with a situation where Sanjuro Tani was tarnishing the name of the Shinsengumi by being too harsh, and she gets further and further involved with the Shinsengumi's affairs. This comes to a head when Okita has her dress up as a woman in order to take a photograph because it might become a keepsake for one of them in the future; Hijikata finds this photograph and is inspired to have "Seizaburo" dress as a woman to gather information on Ryoma Sakamoto, who they have received word about indicating that he is an assassin. She infiltrates an inn he is said to be staying at using an alias, going by the name Sei Matsumoto, and comes to the conclusion that while he does have something to do with the government, he is not an assassin. It is then that she returns to the Shinsengumi and begins living as Seizaburo Kamiya again.
The date of this "special mission" isn't given in the manga (at least, not that I recall; I would have to double-check next time I had access to the books, because the scans online are not complete), but it is likely that historically this is taking place in either late 1865 or early 1866, as Tani's death (said to have happened in 1866) and Itou's defection (in 1867) have not yet occurred.
no subject
Sei's father, who was a western-style doctor from Edo who moved to Kyoto five years previously, and her older brother are killed by samurai from the Choshu clan; she survives thanks to intervention by Souji Okita, who has recently arrived in Kyoto along with the others who will become members of the Mibu Roshigumi. The Choshu set fire to the house and Sei suffers burns, but lives and swears revenge. In 1863, she disguises herself as a boy - going so far as to shave her head into a masculine hairstyle - and attempts to enlist in the Mibu Roshigumi under the name of Seizaburo Kamiya (Kamiya being her mother's maiden name; Seizaburo being a boyish version of her name used as a nickname for her by her older brother). Though she possesses little in terms of technique, she catches the eye of Okita and Toshizo Hijikata because of how light she is on her feet (as she manages not to dodge every strike thrown her way until she faces off against Heisuke Toudou). After it is revealed that "he" is only fifteen, a combination of approval from Kamo Serizawa and her own quick talking prompts Hijikata to allow Seizaburo Kamiya to join the troop. Sei, as Seizaburo, intends to use her membership with the Roshigumi as a way to take her revenge against the men who killed her father, as they were bound to come across the Choshu at some point in the course of their duties.
However, after her first night with them, she is disillusioned by how some of the men (cough, Harada, cough, Serizawa, cough, Nagakura...) act when not on active duty, and she attempts to escape. While doing this she runs into a spy from Choshu who was also attempting to escape, but the pair of them are discovered by Okita, who kills the spy; Sei realizes that much of the behavior she found so distasteful was an act to catch the spy off-guard, but because she
is fucking stubbornhad committed to leaving, attempts to fight Okita and escape. Of course she fails, but their fight is cut short when Okita accidentally cuts open her top and realizes she's a girlbecause her crossdressing was convincing enough for everyone to believe it until they saw boob, take notes, Chizuru Yukimura. After hearing her out, Okita decides that he will overlook the fact that she is a girl, because "no girl would go so far as to shave her head for revenge" - his way of saying that he will accept her as a man and allow her to continue with the troop if she so wishes. And so Sei casts her lot with the Mibu Roshigumi.She begins to get to know the members of the Mibu Roshigumi and meets Hajime Saitou, who in addition to being a friend of her brother Yuuma's, also bears a striking resemblance to him in terms of appearance, voice, and mannerisms - to the point that she initially mistakes him for her brother even though he is dead. She becomes acquainted with the day-to-day workings of the troop and works to hone her skills, often discovering that she still has quite a bit to learn, not just in terms of swordsmanship but also in terms of how the world works and why her comrades live the way they do. She also meets Akesato, who now works as a prostitute in Shimabara but was once called Satono and once was involved with Sei's brother, Yuuma.
Serizawa believes that "Seizaburo" has fallen in love with Akesato, and to help him "be a man" insists that "he" come along to Osaka while investigating rumors that people are using the Mibu Roshigumi's name to extort money from merchants, so that Serizawa can take "him" along to the red-light district in Osaka and help "him" get more experience. The experience Sei gets is not what is expected - in Osaka she encounters the man who was responsible for the deaths of her father and her brother, and has the chance to take her revenge. However, because she has learned that he has a wife and a child on the way, she allows him to live but says that he must repent and support his family - though he kills himself instead for the sake of his samurai honor. After this, she tries to leave the Roshigumi (...again) but after speaking to Saitou, she realizes that she wants to protect Okita (Sei you sweet summer child he doesn't need your protection) and decides to return to Kyoto with them.
It is not too long after this incident that Serizawa meets a woman named Oume, and while watching him struggle to come to grips with his feelings for her, Sei starts to really respect Serizawa for the first time. Unfortunately, his extravagances continue after Oume comes to live with him, and after the Mibu Roshigumi is given the name "Shinsengumi," the order to assassinate him - in order to protect the good name of the Aizu clan and the shogunate - is given. Sei is initially unaware of this order, but discovers it (and that Okita played a part in it) after encountering Okita on his way back from the assassination. This time, she does not try and run away from the Shinsengumi, but tries to figure out what it means to be a true bushi. Not too long after this, she is faced with a dilemma when one of the other troop members is sentenced to seppuku and attempts to escape; she almost lets him go, but catches up with him and executes him for violating the bushido.
There are a lot of things that happen from there, and Sei learns many lessons from various members of the Shinsengumi - most often from Okita and Saitou. The next major historical event that Sei is involved with is the Ikedaya affair, during which Okita is felled and Sei, in a blind rage, blocks a strike with her hachigane before killing some of the other combatants. After this, she is instructed to take Okita back to headquarters and she stays there until he wakes up, at which point she returns to the Ikedaya to help with the rest of the raid.
(...brief, I said, and we haven't even gotten to the end of volume six yet I am so sorry. I'm going to summarize like crazy starting from now because no one wants to read this much and should you need clarification or expansion on anything I can definitely do that.)
As time goes on, Yamanami becomes involved with Akesato, who has been helping Sei keep up with her disguise by allowing her to visit on a "three-day indulgence" once a month to hide her period from the men in the Shinsengumi. Yamanami, being honest, can't bring himself to go around seeing "Seizaburo Kamiya's lover" behind his back, and to try and keep him from confronting Sei, Akesato tells Yamanami that "Seizaburo" is actually a girl. Of course, Yamanami freaks the fuck out, but Akesato convinces him to keep it a secret; he does insist on having Sei wear chainmail under her uniform as extra protection, but this works to Sei's advantage because it helps to hide her feminine figure. There is also a reorganization of the troop and Sei becomes Yamanami's page (look okay now all we need is for another crossdresser to become Kondou's page and she, Chizuru, and Sei can be a matched set).
A man named Kashitarou Itou joins the Shinsengumi to varying reactions from the men. Sei is not overly fond of him, as he is far too touchy-feely for her liking, and she, Okita, and Yamanami devise ways to keep Sei out of his reach. There is a fiasco where Itou is to move into Yamanami's room, but at the last minute Hijikata transfers Sei into the first troop, to be under Okita's direct command. At that point Yamanami and Itou begin to room together and Yamanami becomes caught between a rock and a hard place when Kondou and Itou both try to get him to convince the other that their views are the correct ones.
This situation escalates when a friend of Itou's is executed and Itou blames the shogunate for it. Yamanami, who at this point has begun to see some of the points Itou is trying to make, realizes that he cannot change Kondou's mind and instead chooses to leave the troop, give Akesato's family the money to free her from her servitude in Shimabara, and then allows Okita to bring him back to commit seppuku. Sei is devastated by this, as she and Yamanami had grown incredibly close.
Not long after this, the Shinsengumi's headquarters moves to the Nishi Honganji temple. Sei, who is starting to look more and more womanly as she gets older, struggles to keep her gender a secret; she finds help in the form of Ryojun Matsumoto, a doctor who had been a friend of her father's. When he comes to do an medical inspection of the Shinsengumi, he tells everyone that "Seizaburo Kamiya" is suffering from a rare disease called feminitis, which changes a man's body into that of a woman's. Between his word and the fact that he cited "western research" (which was really just him making things up), everyone comes to believe it because none of them would ever expect a respected physician to lie for the sake of a girl.
With her position in the Shinsengumi secure, Sei goes about her life as a member of the troop. She trains, she goes to Osaka to help with a situation where Sanjuro Tani was tarnishing the name of the Shinsengumi by being too harsh, and she gets further and further involved with the Shinsengumi's affairs. This comes to a head when Okita has her dress up as a woman in order to take a photograph because it might become a keepsake for one of them in the future; Hijikata finds this photograph and is inspired to have "Seizaburo" dress as a woman to gather information on Ryoma Sakamoto, who they have received word about indicating that he is an assassin. She infiltrates an inn he is said to be staying at using an alias, going by the name Sei Matsumoto, and comes to the conclusion that while he does have something to do with the government, he is not an assassin. It is then that she returns to the Shinsengumi and begins living as Seizaburo Kamiya again.
The date of this "special mission" isn't given in the manga (at least, not that I recall; I would have to double-check next time I had access to the books, because the scans online are not complete), but it is likely that historically this is taking place in either late 1865 or early 1866, as Tani's death (said to have happened in 1866) and Itou's defection (in 1867) have not yet occurred.