The Last Tsugikuni

Yoriichi Tsugikuni was the first demon slayer to create Sun Breathing and the man who scared the demon king Muzan Kibutsuji. Unfortunately, most of the Tsugikuni family died out. Luckily, one child of the Tsugikuni clan managed to live and his name was Jin. But he wasn't called Jin Tsugikuni; instead, he was called Jin Aizawa. The reason for this is when Jin was still an infant, his parents took him down a river to save him from being killed by a demon. And once Jin was safe, an elderly couple named Makoto and Kaori Aizawa found the baby and took him in. Little did the couple know the child they adopted was going to be unlike any of their own children they had before.