Do you mean where he was visiting Sayoung in the hospital again? I think that's bcs he was thinking about the past when he didn't have the white hair yet, you can see it in a few panels since his original hair colour was black
his hair turned white after he came out of the rift! so his hair was brown before he went in
cause he hadn’t gone into the long rift at that point, it turned white while he was stuck for ten years or however long it was
ohh mb i thought his hair was originally white, thanks for clarifying that
Wait I have a question, wasn't J's haircolor supposed to be white?? Why is it that in the flashbacks it was brown??
Ps. I'm not a novel reader but I remember that detail where MC dyes his hair as disguise