Kokushibo finds his descendent and takes him back to the infinity castle, his grandson is a slayer- but also a Hashira but he's 14 so- it's fine, the grandson of Kokushibo is named Muichiro and he's 14 but looks like a girl-(Muzan is the demon king, and Doma is gay/fruity asf- and Kokushibo has 6 eyes since he's uppermoon 1-)

1: Muzan 2: Kokushibo 3: Doma 4: Akaza 5: Nakime 6: Hantengu 7: Gyokko 8: Kaigaku 9: Daki 10: Gyutaro 11: Muichiro