Demon Slayer: the Demon Slayer's Journey of the Three Swordsman Swordsman

[Weak system + single heroine Butterfly Ninja + not dismantling the original wife + making up for regrets] Growing up in a kendo hall, surrounded by the warmth of his master and senior brothers, Akabane Yuuto thought he would spend this life in an ordinary way, but the arrival of the "ghost" changed everything. Seeing his relatives die tragically in front of him, but he was powerless, the young man's hatred finally awakened his golden finger. Amidst the evil ghost's playful laughter, the flying sword energy penetrated its neck, and a voice sounded in its ears: "Eye, ear, nose, tongue, body, and mind are the six sense organs of a person, plus good, evil, and peace! Each has peace and pollution, which is exactly the thirty-six troubles in one life. Ichidōryu·Thirty-six troubles phoenix." Basic breathing techniques? I can't, but I know ghost's breath. "He Dao"? I don't have one, but I do have a "black knife." "Transparent world"? I can't understand it, but I can smell it. "Stripes"? Sorry, can you hear about "overlord color"? Let's watch the young man kill all the evil spirits in the world with his swordsmanship. [The introduction is too weak, please move to the text]