Many people do not realize this, but Okita and the Shinsengumi actually existed! Check out the Shinsengumi page for more (breif) info on the group. Here is info on the real Okita, who inspired many fictional representations of himself, as well as Watsuki Nobuhiro's Seta Soujirou of Rurouni Kenshin.
Name: Okita Souji (Soushi.... it's an ongoing debate...)
D.O.B/D.O.D: ??.??.1842 - 30.May.1868 at age 25
Marital Status: Single, and furthermore, there is no evidence he ever had a lover.
Physical App.: Aside from just being a Japanese male, it is said that he always had a smile on his face (rumors of him being extremely good looking are only that, it was a bad translation that got spread around on the net). ^.^;
School: Tennen Rishin Ryuu
History: Born Okita Soujirou, he was an accomplished swordsman by age 15, having joined a dojo at age 8 to train under the 4th master of Tennen Rishin Ryuu, Kondou Isami Masanobu, and beating kenjutsu master in the Shirakawa fief (where he was born) at age 12. In July of 1862 while teaching kenjustu in Edo he got the first of bad illnesses, measles. Later, Okita was the captain of the first troop of the Shinsengumi, and quite possibly the strongest of the bunch, able to wield a katana, bokken and shinai equally well. It is said that his skill made him surpass even masters from other schools along with his own comrads. He is best known for his 3 thrust technique, the Sandanzuki, which is a poke to the neck, then left shoulder and right shoulder. So, all was going grand until after the formation of the Shinsengumi, when he contracted Tuberculosis, which was, at that time, incurable. After especially strenuous physical exertion he would cough up blood, but attempted to hide his illness from the rest of the group. There is a rumor floating around on the net that during the Ikeda-ya affair Okita-san coughed up a great deal of blood and fainted, however, as stated, this is only a rumor and very incorrect. The Ikeda-ya affair occured too long before his death, TB kills in a shorter amount of time. Sometime later Okita-san became obviously ill (I'm still working on that translation). It was agreed by Kondo and Hijikata, who felt like elder brothers to Okita (10 and 9 years older, respectively) that the prognosis of Okita's condition should not be well known. Having survived the Boshin War, Okita was admitted to a TB hospital in Edo (modern day Tokyo). He died there in 1868, the first year of Meiji (all alone ;_;), and is buried in the Azabu/Roppongi area. Of some note, Okita had an elder sister. It is debated whether she died while he was young, or if she survived him.
Personality: Though he was generally feared for his ability and occuaption, Okita-san was frequently seen playing with kids, and was well known for his good humor and gentle nature. It is said that he would much rather joke and laugh then to be serious, but when he learned of his illness his smile was faintly shaded with a deep sadness (mine would be too).
Mistake in the ADV OVA Dub: At one point during the second (I belive. Perhaps the first) OVA in the ADV dub, Okita calls Saitou "Master". This is wrong wrong wrong! Not only is it not true to the Japanese version (you'll see that if you watch the subtitled version), but it is also historically inaccurate, which I dont think ADV knew when they were messing with the script. Okita Soushi, as previously mentioned, was the Captain of the First Troop. Saitou Hajime was the Captain of the Third Troop. They were of equal rank. Furthermore, Saitou Hajime had nothing to do with any of Okita's training. There is no reason historical, or in the RK OVAs that Okita should be calling Saitou "Master". Sorry to rant, but that just made me so mad!