After centuries of defeating Muzan and traveling the world as a Demon, Tanjiro Kamado decides to live a steady life in New York, living his days in peace. The last thing he wasn't expecting was to see some espionage named Shield asking him if he wanted to join a certain initiative.

Logan Stark. the famed Iron Lad, the next Iron Man, dies using the Infinity Stones. Now transported back to the Taisho era, but not his own. He is in a alternate universe, where demons prowl in the dark hunting human to eat. Now armed with the Infinity Stones, Logan will join the ranks of the Demon Slayer Corps. He will slay demons and avenge those killed by demons. M for gore.

When Nezuko was reborn, this was not what she was expecting. (Or, when Nezuko gets dragged into the Avengers via her uncle.)