I have been thinking about the underlying theme in Wano... Without a mistake, it is betrayal.
The first betrayal came from Orochi's grandfather, he betrayed the Kozukis, killed all other daimyos and was forced to commit seppuku because of it. His clan was persecuted due to his actions and innocent people lost their lives.
Then, we have Orochi's revenge, he betrayed Oden and Sukiyaki with a greater goal, to ruin Wano and make its citizens suffer because, in his mind, they are all guilty for what happened to his clan. Orochi made a promise to Oden that he would free the prisoners and leave Wano once ships are built but he never intended to keep that promise.
We have a mysterious man working for Orochi, loyal to a fault, yakuza boss of the capital, shogun's guard dog - Napping Kyoshiro. Turns out it is Denjiro, who has been waiting for the right time to drive his blade through Orochi's throat. The loyal guard dog has never been loyal. All the money he could get his hands on, together with Hiyori, was distributed to Ebisu town.
The oscar goes to a member of Red Scabbards, the man who was sharing joy and sorrow with them all. An actor, who didn't love the Scabbards nor did he hate them but found his one and only purpose in playing a character on orders of his master, lord Orochi. The one and only, Kurozumi Kanjuro, the man who "couldn't draw".
Was that the last betrayal we will see in Wano? Just another betrayal we found out in Wano was Apoo betraying Kidd and Hawkins alliance by working for Kaido. At the same time, we found out about another betrayal, X-Drake as an undercover marine officer of the secret organization Sword was never loyal to Kaido. The newly formed alliance between the two Yonkos could perhaps end with betrayal and the alliance between Strawhats and Heart Pirates is of uncertain epilogue.
Who is the best backstabber of them all?