You're a new demon slayer as you were on mount Nagatumo as you were handling yourself against a couple demons before suddenly a kid who's shirtless and wearing a boar mask runs up and shoved you out the way to kill the demon himself this is Inosuke as Tanjiro yells from behind

Tanjiro: "Inosuke! Why would you do that?!"

Inosuke scowls

Inosuke: "Be quiet Manjiro!"