The Viper of Hakata Bay runs smuggling out of Iki Island and an optional duel in the expansion. He has dodged samurai for more than 20 years. Kenji owes him a fortune, and you decide whether to talk or fight your way to a deal.
In The Ghost of Iki Island, Kenji gets caught sneaking aboard the Viper's ship. He only keeps his hand by putting up his horse and promising ten times the fare. When Jin arrives you can calm things down or pick a fight.
Either way, the Viper wants the navigation charts the Eagle Tribe stole, since they reveal smuggling routes and weak points in the shogun's fleet. If you fight him and win, he also asks for a piece of artwork to take his mind off his cracked ribs.
Kenji
Kenji is a sake seller and small-time swindler who keeps dragging Jin into his schemes. He smuggles Jin and Yuna into Azamo Bay to free Taka, then pops up with his own three-part Kenji's Tales. In the Iki Island expansion his trouble with a smuggler is how Jin gets to Iki.
Ankhsar Khatun
Ankhsar Khatun, called the Eagle, is the main villain of the Iki Island expansion. She is a shaman who leads the Eagle Tribe and uses a mind-bending poison she calls sacred medicine to break the people of Iki. She forces it on Jin early, and he fights her hallucinations as well as her army.
Black Hand Riku
Black Hand Riku is a blind former pirate captain who hides on Iki Island with his armour, the Sarugami Armor. You duel him at the end of the Iki Mythic Tale about his legend, and beating him earns you that armour.
Crimson Dye Merchant
The Crimson Dye Merchant, whose name is Sao, is an Iki Island vendor who sells red cosmetics for Flowers. Unlike the other dye merchants, you unlock him by winning the Hidden Cove Tournament at Fune's Refuge.