Is there any way to make yellow hair gradually turn into black hair?

Eat more walnuts, sesame seeds and eggs, and ask mom to make you black rice or black bean porridge. Your hair will turn black.

Also, don't blow your hair with a hair dryer. Don't be too windy or too close to your hair. It will burn your hair (it will be better to soak your hair in tea after washing).

I envy your natural yellow hair, and I want to dye it.

I hope I can help you ~