Total War: Shogun 2 - Fall of the Samurai: The Tsu Faction Pack

Summary pulled directly from Steam - Some text may only be applicable to Steam platform

The Tsu Faction Pack adds a new playable faction to Total War: SHOGUN 2 - Fall of the Samurai, previously only available in the Steam Special Edition, for use in single or multiplayer Campaign modes and Custom and Multiplayer Battles.
Rising from humble roots, the people of Tsu are wise, artful and astute strategists. Their use of Ninja is unsurpassed on the battlefield and in covert operations.

Faction Traits:

Persuasion (+2% to allegiance conversion)
Fortitude (+1 to unit melee defence)
Furtiveness (+3 to the number of kisho ninja units available)
Artifice (-10% to the cost of shinobi actions)

History of the Tsu

The Betrayers

The Todo clan, rulers of the Tsu domain, cannot claim a proud samurai lineage like many of the other great clans of Japan. Their beginnings are actually rather humble: Todo Takatora was an ashigaru, a peasant footsoldier, during the great wars of the Sengoku Jidai. So what? So too was the mighty general Toyotomi Hideyoshi, revered as one of the three great unifiers of Japan! Todo Takatora was wise enough to side with the Tokugawa clan at Sekigahara, and he was rewarded with the fief of Tsu, comprising a good part of the provinces of Iga and Ise.
Historically, the Tsu chose to play a "long game", apparently supporting the Shogunate until the very last moment. At the Battle of Toba-Fushimi they sided with the Choshu and Satsuma domains, and therefore with the Imperial forces. They then provided the Imperialists with a strategic position to continue the drive towards Kyoto. Their central position on the mainland, in what is now Mie Prefecture, lay between Edo and Kyoto, and this allowed them enviable flexibility and options in their loyalties. Such flexibility goes some way to explain why they have such excellent shinobi at their command.