Responses
I'll make it short, SPOILERR
It includes the 2nd time line (where the student show the fragment of another world, that is the 2nd timeline) , which is almost the end of the world and he's slowly becoming a monster, (like in those rifts, dungeons) and it's because the 2nd time line and current time line is colliding

I genuinely thought his hair turned white because of stress. I feel so stupid