It was set in old timey Japan but not like old old days. The mc is adopted by an old man and another younger boy is later brought in. It has hint of shady very gross stuff regarding the adoption. Mc worries about being replaced soon and he like planned to run away with a boy from his school. There was also a mystery of the mc and little boy being bird like creatures. I cannot for the life of me remained the title TT-TT please help

It must have been a murim manhwa, I saw a review on youtube and it started in a pleasure district. It was not perverted or anything, Mc (male) was living there and they got attacked? And he was the only one who fled, my memory is not very clear.
But if there's any murim manhwa where the setting of a really struggling Mc starting in such a setting, please do tell