A very powerful immortal cultivator from the immortal realm died and got reincarnated to a low martial world like murim.
this cultivator lived in a mountain secretly and never leaved and because he is a cultivator who cultivated immortality, because of it some rumors will come as he breakthroughts and cause heavenly tribulations thus making the whole place as the most dangerous in the martial world.
And when he reached golden core he have already become invincible in the whole world, so when that happened he left his home and on the way he spotted a familiar face and then left the place because he thought his childhood friend died.
But he didn't know that his childhood friend is still alive and they just walked past each other, his childhood friend along with a group of people visited that place in order to investigate it.
They should known each other, but the way his childhood friend looked at him is different as he looked like a cute girl when they were still kids, and now he looked different as 30 years have passed and his childhood friend think that he is already looked old not young as he did not practice martial arts, what his childhood friend remember.
Because of the effect of cultivating immortality the higher realm you reach the lifespan will grow and made him younger.