Demon Slayer Naruto

After he lost in the 4th great shinobi war, everyone is dead, except for him. Even Kurama was gone because he had to use Barion Modo to stop kaguya (coupled with rikudo senjutsu and rikudo Senji Modo (I say senji since senji means sage and sennin means hermit) he didn't have the bad affects, so he could think and stuff, but since Kurama is gone, he is now techinically in Naruto's chakra system).
This gave him time to read up on things to figure out how to restart it all and save everyone. He even came across this weird thing, the 7 heavens breathing method, and decided to learn it.

Anyways he tried the jutsu-shiki to send him back in time, but, he got sent to a different multiverse entirely (you need to stop putting in too much chakra to things, Naruto) and was reborn as Kamado Tanjiro's younger brother.

He will create his own style, called Rikudo (six paths) but there will be 7 forms (if you could call them that), being wind, lightning, healing, stone, fire, earth, water, which allow him to control the respective element except stone, which uses senjutsu to turn people into stone, and enables him to use the orbs of truth and the sword of nunoboko, and fire, which allows him to use sasuke and itachi's black flames, being as hot (or hotter) as/then the sun breathing.
Also imagine this: Kiba as Inosuke