Ryuichi was an Imperial agent back in Kozakura, devoted to the security of the Shogun. After a specially vicious attempt at the Shogun's life, public face needed to be restored, and thus some agents were required to carry the blame. Ryuichi was cast away, and he accepted the price to his own honour in exchange for duty. He was born and raised for that.
He traveled far away, to the distant Faerûn, escorting a caravan as a nameless merecenary without honour - a ronin. He tried to make a living selling his physician skills, but the lands of Toril are perilous and deadly. Ryuichi - and the rest of the expedition - found their demise at the hands of some powerful sorcerer-raiders half way to Thay.
That's not the end of the story, though. Thanks to a spirit talisman he had received time before as a reward for his services, Ryuichi's spirit was preserved and transferred to another host (a one-time Reincarnate effect). Our hero awakened himself many miles away, soul intact, but inhabiting the body of a female half-orc.
That was a hard blow for him, but he recovered, thinking there must be a reason why the Kami wove this destiny for him. Getting used to his new found physical features, he traveled here and there through Faerûn, aimless, trying to find a purpose and make sense of his weird experiences. Willing to help common people defend themselves against the evil powers, he recently ended up in the Spine of the World area, where he's heard about Duergars being a growing danger.
