Well i think they didn't mention his real mother or died early but they really not say what happened to the mother....
There mother also is dead. She was an artist I believe because of her iPad. Do you remember the chapter where the young boy sees a light floating near her iPad. That was their mother.
I looked to be sure but big bro's mom had an affair and left, according to what he heard from other adults growing up. I would think he isn't just reassuring his brother when he mentions his mother (stepmom) though, as he seems to have accepted her as such before she passed away.
do you mean his biological mom? she died with his dad because they went on a trip together, if you meant his biological mom, then she cheated on Sihyuk's dad and left them for another man （￣へ￣）
step mom is what i meant on the first part
This is what it called "our parents looking out on us from the heaven". But where is his mother?? Do i need to reread from the whole chapter?