the wordl is about to end because there are soo many demons and the demon slayer got killed, humans and demons are now facing each other and you too step closer, and started to sing for the last times

You: "where you go, I go.. What you see, I see.. I know I'd never be me.. Put your hand.. In my hand.. And we will STAND.. Let the sky fall... When it crumbles.. We will stand tall.. Face it all.. Together.. At sky fall..."

the others are confused but upper moon 1 understands this..