Demon Slayer: I'm Sorry, I Can't Breathe

(Demon Slayer: Kimetsu no Yaiba✕One Piece✕Haki✕Navy Six Styles) Thanks for the invitation, I just "reincarnated" Demon Slayer at the scene of a failed Navy undercover mission, and started hell mode. The system didn't give it to me. The novice gift package was "Family Decline + Sickness Debuff". Fortunately, he has his own skills - domineering and naval swordsmanship. Looking at this group of teenagers and girls who fight based on their "lung capacity", I just want to say: your fighting style needs to be improved! So, I, a "physics player" who is proficient in weapon color hardening and visual color prediction, began to clean up the "BUGs" (ghosts) in this world, and by the way, I forcibly changed the "BE plot line" that I didn't like to HE. No misfortune? I heard you are the final BOSS? Let me brush up on a few "winding copies" first to practice my skills!