We don’t know much about the Kwon family, maybe they have a sister too, and also after your comment I watched that picture again and that is not his hair, that is his part of his head “muscles?” or how can I say.
Also, where did u find out the author changed his brothers age from 29 to 26? I didn’t see that.
I really want the sibling to be that person, and yes, the timing looks perfect to be both the same. But I find it weird that the picture ( the one that the classmate showed him before entering the bus), the eyebrows are even blonde, not just the head. Someone in the comments below said the author talked about a fix in the brother’s age. The article said he was 29 but it’ll change to 27 ( I haven’t confirmed). I just don’t want my hopes up

The time will practically come when the TOP will introduce him to his brother, who will obviously be the boy from the school that the BOTTOM was in love with. From here the TOP will understand that he is jealous rotten and bum bum bum