Six Eyes Starting in Demon Slayer: Kimetsu no Yaiba

(Things won't get too over-the-top. The Six Eyes need to grow too; having someone like Satoru Gojo fight Muzan would be overkill. I probably won't include a female lead, though pairing him with Shinobu might be nice too. I won't break up any canon couples. If there are problems with the plot, I can change them.) A die-hard anime otaku unexpectedly transmigrates into the world of Demon Slayer: Kimetsu no Yaiba as an ordinary person. One day, while out gathering medicinal herbs, he encounters a demon. On the brink of death, his intense frustration at being unable to change the original story's heartbreaking outcomes despite transmigrating successfully activates a system and grants him the "Six Eyes" (juvenile version)...

The figure who fell with a valiant smile beneath the rising sun after the Mugen Train~ The girl who finally smiled beneath a Wisteria tree... This time, I will change everything!