Nine Red Scabbards

The Nine Red Scabbards are a squad of samurai who served Kozuki Oden. Their captain is Kin'emon.

Overview
The Nine Red Scabbards are said to be a formidable group of fighters, so the story of Kurozumi Orochi defeating them granted him the status of a great warrior. They are led by Kin'emon, a powerful swordsman with the ability to cut fire, that even the current leader of Wano Country's Yakuza, Kyoshiro, showed interest in fighting against.

Members
The only known member of the group is their leader, Kin'emon.

Past
At a certain point in the past, the group was formed and served under Kozuki Oden and the Kozuki Family.

20 years ago, during the Beasts Pirates takeover of Wano Country, they were supposedly taken down by the Shogun Kurozumi Orochi, for the family's plan to open up the boarders of Wano. Despite their defeat, it was prophesied by Kozuki Toki that they will return 20 years later to claim their vengeance.

In truth, Toki used her Toki Toki no Mi abilities to send Kin'emon and his group to the designated period, ensuring at least one member of the group would resurface.

When they arrived, the majority of Kin'emon's group exited Wano in search for allies in their mission. However, they came across several problems along the way and got separated.

Supposed Legacy
Due to Toki's prophesy, Orochi became wary of the return of the Nine Red Scabbards, much to the ridicule of his close allies, who believed all of the group's members were dead.

Meanwhile, the family's followers waited for their return.

Punk Hazard Arc
After tracking Kozuki Momonosuke to Punk Hazard, Kin'emon encountered Trafalgar Law of the Shichibukai, who used his abilities to separate Kin'emon's body, until he was reassembled with the help of the Straw Hat Pirates, who also helped him locate and rescue Momonosuke. The two then traveled with them to Dressrosa.

Dressrosa Arc
On their journey, Kin'emon explained he set his goal in Dressrosa to locate his friend, and then proceed to Zou for yet another ally. After finding Kanjuro, the two helped save the country from Doflamingo's reign, before continuing with their new allies toward Zou to reunite with Raizo and Momonosuke.

Zou Arc
Upon reaching Zou, Kin'emon and Kanjuro were separated from the group, and only join later much to the Straw Hats fear of the samurai encountering the Mink Tribe. However, the truth about Kin'emon's allegiance, and about the relationship between the Minks and the Kozuki Family, brought upon the formation of Kin'emon desired forces in the form of the Ninja-Pirate-Mink-Samurai Alliance, and the group made plans to meet back at Wano Country.

Wano Country Arc
After Luffy's group arrived to Wano, they met Kin'emon at the ruins of Oden Castle, who revealed to them his true story.

Trivia

 * Despite also being retainers, Kanjuro, Raizo, Inuarashi, and Nekomamushi, are not confirmed to be part of the group.