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the memory tanjiro is seeing is not the swordsmen. He is seeing his ancestors memory, the one in the green and black kimono that looks like him. tanjiro and his family are not related to that swordsmen. and keep in mind that memory is 300+ years old. I wont spoil the connection though

Sun Halo Dragon Head Dance was incredible

I don't think that upper rank demon and the legendary swordman are the same person, every time we see tanjiro berserker, the demons are literally terrified and start to trembling! So I don't think Muzan himself transformed the 1st swordman into a demon! Further more , every demon says that he almost decapitated muzan!my theory is that he defeated Muzan but he spared him showing mercy ( no spoilers please 🥺🥺🥺🙏🏼)

ok

Yoriichi and Upper rank 1 were brothers they are not same one was sun breather other is moon