He is wearing a Charlie Chaplin mask, which has a smile drawn by blood, and a black suit. He slowly moves towards the car. Tanjiro starts to panic, but that is when Tanjiro notices that he has an iron rod in his hand. He becomes restless and tries hard to move the car, but fails.
The man stands right outside his car door and tries to open it. Soon he smashes the window and unlocks it from inside, even when Tanjiro tries to fight back but fails. They both fight. Eventually, Tanjiro gets hit on the head by the iron rod.
Tanjiro is unconscious, so he leaves him all alone on the road. Before the man leaves, he leaves his mask and a piece of paper on which 'Revenge' is written with Tanjiro's blood.
Kosei's pov
I was on my way back from work. It was a long drive, and I was completely exhausted. That was when I noticed a car in the middle of the road. I decided to wait for some time, but the car didn't move. I started pressing the horn multiple times, but there was still no response.
Sensing something was wrong, I got out of my car and slowly approached the other. The window of the car was smashed, and there were blood stains on the car. Soon after, I notice someone unconscious on the ground with blood all around him.
Approaching the body slowly and steadily, I turned the man over only to find my own brother, Tanjiro. I immediately kept his head on my lap and tried hard to wake him up, but failed. Lifting him up and putting him into the car, I start driving to the hospital at full speed while shedding tears.
As soon as I reached the hospital, the nurse brought a bed to lay him on, and soon he was taken into the ICU.
I was still scared and worried; I was feeling so restless. I was walking around the place, panicking while asking about him every 5 minutes. After what felt like years, the doctor finally came out and told him that he needed blood immediately. While offering my own, I started praying for the best.
(Time skip)
I'm talking to the doctors about Tanjiro. They told me he was fine but needed good rest as he was badly injured. I went in and sat next to him. I held his hand gently when, suddenly, his eyes started to flutter and he soon regained consciousness.
Overjoyed, I immediately informed the doctors, and they rushed in to check on him. After a while, they allowed me to go in.