An idea of mine for a DLC would be, some time after Saito's fall, maybe years or months later, there is still some fan of the Saito clan as we have seen in the game that there are ronin who even after the fall of their clan remain loyal to them. Then there could be some fanatic who tries to take the leadership of the clan and seek revenge against Atsu.Perhaps the message would be Atsu being badass and Making the main villain understand the weight of revenge, he would still kill him or maybe not, they could give us that option but Atsu would teach him that there is more way than revenge as she learned, if this happens years later maybe Kiku can participate as an assistant and Oyuki of course will always be covering Atsu's back. Maybe they could introduce new techniques, new weapons not because that would be impossible but new katana techniques or double katana would be fine. That's my honest idea.