Kanjuro despite being the second of the Nine Scabbards to be introduced was never given much focus.
Kinemon was a big part of Punk Hazard, Raizo was the main focus of Zou, but all Kanzuro was apart of was a small side story in an already dense Deressrosa Arc. He was always in the backgrounds, an irrelevant side character almost, which now I realize was on purpose.
Kanjuro was born and raised in a popular theatre troupe. However, his parents were killed onstage one day due to being members of the Kurozumi Family. Kanjuro drifted and ultimately found his relatives Kurozumi Orochi, Kurozumi Higurashi, and Kurozumi Semimaru. So that Kanjuro could aid in his plot to overthrow the Kozuki Family and become the shogun, Orochi gave him a Devil Fruit to eat and instructed him to live as a Kozuki member up until his death. Since he sought death, Kanjuro readily agreed.
The only life Kanjuro knows is the one lived on stage pretending to be someone else. He laughes when it is appropriate, cries when required and harbour no ill will towards other “actors” in the stage that most people call life. He plays the part of traitor because that is the role bestowed upon him and when it is time to reveal himself he has an evil face on as now it is the time to play the “bad guy” role. This is most brilliantly depicted when he meets Orochi and he has the form of a blob that has no definite dimensions and can change shape according to the “vessel” that he is put in. He is willing to die to fulfill the role he is playing and I think that is the most brilliant part of his reveal. Simple but brilliant.
Now regarding the future of his character, I think it will be interesting to see the way his character goes now that he is releaved of the role of the character. Will he take the role of the evil guy and die fullfiling the role or will he have a redemption?
Seeing how Oda redeemed every “traitor” character he wrote and made the good guys forgive them (Squardo, Viola, Pudding), how the real Kanjuro was introduced as a victim, and how he doesn’t really hate Oden nor the Scabbards, it’s very unlikely that he’ll just die as a villain. He could die as a good guy, but I personally think he’ll find the joy in living and choose to do so. This might happen to maintain the Kurozomi bloodline in Wano. A story of forgiveness.
*Theory by Boundman101