Unifying the Ninja World: Starting from Demon Slayer: Kimetsu No Yaiba

Kizai traveled to Naruto's world. He is a commoner, has no Sharingan, and has no Wooden Release. There's just a system that doesn't move. When Muzai was seven years old, the system suddenly issued a mission to avenge Muzai, a fellow demon from another world! Kill Muzan Onimbutsuji! Mu Zai can only say, I can't beat him? Don't go! The remnant soul of Demon Slayer Muya in the system smiled slightly. The ninja world has begun to fight World War II. Your chakra does not even have 0.5 Cards. Only time travel can give you time to develop. Faced with the sad reality of the Naruto world, Mu Zai had to choose to fight Muzan. But I just want to live until the end of my life! (This is a newcomer's first work, come in and take a look! Ernegay! The author can do everything!)