What if tanjiro got the carnage symbiote?

Prologue

Tanjiro kamado was a boy like any other,he had a family and lived in the snowy hill.
He wakes up on a day like any other.He bids his family farewell and gets coal from the outside.As he gathers coal,he suddenly sees a light from the sky.He looks up and sees that it's a meteorite.He sees it head in his house's direction.He worries for his family and runs home.As he returns home,he sees the meteorite feet away from his house.He enters the house,but as he does,he sees his families bodies,scattered around the house.He looks around in horror and shock as tears fly from his eyes.He looks at his little sister,Nezuko.But as he looks at her body,he notices her twitching.She's alive!Tanjiro immediately picks her up and runs out of the home,only to meet an unfamiliar man.

Tanjiro:H-hello?Please help!My sister,she's-
Suddenly,Nezuko moves and jumps off of Tanjiro.The two men look back at Nezuko to see that her eyes have changed,they're feral and bright pink,and her teeth have become fangs.
Giyu:She has become a demon.
Tanjiro:A-a demon?
Suddenly,giyu pulls his sword out and pulls it back.
Giyu:She must be ended.
Tanjiro:Wait!No please!
Giyu ignores Tanjiro and charges at Nezuko, but as he swings his blade,Tanjiro steps in front as his chest is sliced open.Blood bursts from his chest as Tanjiro falls backwards.Giyu widens his eyes in shock as Nezuko falls to her knees.She grabs ahold of Tanjiro as Giyu was lost in thought.Unnoticed to everyone however, the meteorite broke open as a black living liquid left it's physical containment.The liquid looks around and sees Tanjiro.The liquid moves quickly and slippery.It moves in front of Giyu and Nezuko,it rises up and dives into tanjiro's wound,shocking the two.Tanjiro's body shakes and gyrates as his jaw falls wide open.

In Tanjiro's mind
Tanjiro looks around but sees nobody.He wanders through the unfamiliar space.Finally, he sees a red humanoid.Getting closer,he sees it has no factual features and is about 8 feet tall.
???:Hey there.
The humanoid spoke nonchalantly.
Tanjiro:Where am I?
???:In your head.Wanna get out?
Tanjiro:Yes please!My sister needs me and-
The humanoid waves his hand.
???:Yeah yeah I know I know.Let's just do this.
Tanjiro:Hmm?Do what?
???:You'll see.

Back into the real world
Suddenly,tanjiro stands up as the wound on his chest closes.Giyu steps back and prepares his blade again.Suddenly,a red liquid emerges from Tanjiro's skin and covers his whole body. Tanjiro's body grows as he becomes 8 feet tall. He speaks in an unfamiliar tone with a beastly voice.
???:That...