Chapter 921 introduced Shutenmaru, a master thief, skilled enough to steal from Orochi’s farm without being stopped by any of the samurais or Beasts Pirates working under the shogun, and to hide from them for weeks without being discovered.
A testament to Shutenmaru’s combat abilities is that Kaido, one of the Yonko, wants him to become his subordinate. The Beasts Pirates respect for Shutenmaru also manifested when Holdem believed that Monkey D. Luffy’s strength made it likely that he was Shutenmaru’s subordinate.
Despite his large size, Shutenmaru is extremely fast, being capable of charging towards Jack in a instant. He also possesses a fair amount of endurance, as he was seemingly unaffected when Jack cut him in the shoulder.
Shutenmaru is a powerful master swordsman. With one slash, he was able to give Jack a large cut across his chest and break one of his shotel blades. He then proceeded to fight evenly with Kaido’s right-hand man in what spectators considered to be a high-level duel.
Well, I believe that Shutenmaru is Ashura Douji.
Ashura Doji is a resident of Wano Country. He was once the most dangerous man in the formerly lawless region of Kuri before being defeated by Kozuki Oden.
Shutenmaru only respects strong Samurais. In chapter 921 he said “ in this country there are no real men, who strong samurai (like himself) would join. The days of Wano are numbered.”
I believe Shutenmaru is waiting for someone like Oden.
Shutenmaru was a honorable Samurai after Oden defeated him, now that Oden is deceased Shutenmaru went bad again, he’s a troublesome bad man, when he will see Zoro he will be a good Samurai.
Furthermore Zoro said in Zou, that he will gather all Samurai together for Luffy.
Maybe Zoro will fight and defeat the leader of the Atamaya Thieves and Shutenmaru will join the strong leader of the Samurai Zoro.
Zoro will be the leader of the Samurais that Ashura Douji aka Shutenmaru is waiting for and Zoro will make his promise true to gather all Samurais in Wano together.
What do you guys thing? Could this be true?
*Theory by Saikō no Kenshi