*!Spoiler!*
*!Alert!*
*1st idea
Kanao and Tanjiro are childhood friends but don't remember each other then met again by bumping into each other
**2nd idea
Demons excist in this world and Kanao and Tanjiro bump into each other then became good friends then turned into couples and both are afraid of losing each other
***3rd Idea
Will just be like Highschool musical
****4th idea
Kanao doesn't like Tanjiro but ends up liking him.
5th Idea
The demon slayers are reborn but doesn't remember there past life and when Tanjiro and Kanao met they began to have flashbacks and dreams of there past life.