thinking about nomu mic au yeah yeah but he and aizawa were fiances that lived together before he was captured and nomued. it was largely assumed that he ran away/betrayed hero society
after no sign of mic for months aizawa snapped. he got rid of anything and everything related to mic that he could, going as far as to rip him out of old photos of the rooftop gang. nemuri was concerned and secretly held onto some of the important nostalgic stuff, but everything else was purged.
a few years later, they discover mic was nomued (to some degree or another, maybe his memories could be recovered, maybe not). aizawa goes home and looks for something of mic's. anything. he cant find it. not even pictures of the old rooftop gang. aizawa eventually has to ask nemuri for something, and that's when nem comes clean about the box of hizashi's things that she squirreled away. aizawa can't find it in him to be mad, he's just regretful that it came to that in the first place.