Kaito Makoto:
It occurs to me that I don't actually know anything about the Tortoise Clan, other than that I'd assume they were one of the minor ones.
The Tortoise Clan is super duper weird. Technically, in the Imperial histories, they're the personal servants of the Emperor, and the Clan built around the Kami Hantei. However, they've always played second fiddle to the Imperial Families (who technically serve the Imperial Throne, not the descendants of the Kami like the Great Clans). As such, they've basically devolved into a band of low-lives and semi-criminals, using their monopoly on the docks of the Imperial capital to extort the Crane, Mantis, and Yasuki, and run protection rackets throughout Otosan Uchi.
In reality, they were the crime syndicate running Otosan Uchi when it became the capital of the Empire, and now they're used by the Imperials to do all the shady shit Imperial honor doesn't allow, and can't be outsourced to the Scorpion or Ikoma, including conducting a swift trade in gaij- hey look at that dog!
They actually become integral to the Mantis Alliance during the Clan Wars because they were the only minor clan with a formalized courtier school and ties to Imperial Families and almost (and in my opinion should have because their daimyo had just been exploded by demons) swore allegiance to the Mantis after the Clan Wars.