The Otomo Clan has been released upon Total War: Shogun 2 players via DLC as of today. The Otomo were previously an NPC only clan, a group of successful traders who allied themselves with the Portuguese. In return, had influence and benefits from trade while helping spread religion. The Otomo are also well-versed in firepower, having pioneered gunpowder in the era. This made them, naturally, in a prime position to trade with the West as well as a potetially wealthy and dangerous clan to oppose. They have benefits to wealth and trade, as well as some lowered costs.
Now you can get the Otomo Clan DLC pack, which includes five new units,--four land and one sea--the ability to lease land to the Portuguese, providing instant wealth, as well as a research chain that leads to Hospital, seminary, and finally, Jesuit College to encourage Christianity to spread.
You can get the Otomo clan DLC on Steam.