You know what scene I still think about a lot? The conversation with Garaki and Mic.
Well, it's less of a conversation and more Garaki infodumping to cause as much emotional damage as possible before he gets his ass thrown in jail.
Still, all of the information we ever get surrounding nomu and Kurogiri specifically is so chilling. And if you've read the School Days arc in Vigilantes it's WORSE.
In Vigilantes, Oboro's death is framed by the narrative as an accident, a tragedy that comes as a result of educators and the government being too eager to throw prospective hero students into the world and out of their depth (wow I wonder where I've heard that scenario before). Shirakumo and Aizawa are in a fight they are not equipped to handle, and Shirakumo pays the price by protecting others over himself. He didn't do anything "wrong" for this to happen, but it happened anyway because the world doesn't care if you were in the right or not when it snuffs you out.
This isn't just a tragic backstory for Kurogiri, it frames Aizawa's entire mindset as he grows into an adult. His beliefs and unorthodox teaching methods come as a result of what he took away from thet tragedy. He emphasizes the unfairness of the world on the first day of class. He refuses to coddle his students. He's against the first years taking work studies. He fully intends to expel students who will not take this training or their own well being seriously because if he lets them stay, they're the next Shirakumo.
And then there's Garaki, all too happy to bring up Oboro to Mic as he's dragging his fat ass out of the lab. Because, you know, fun fact, that attack wasn't a coincidence at all. No bad luck, no wrong place wrong time, because that little work study team was All For One's target. He wanted a new quirk in his repertoire. It's just a shame that they got the wrong one. That erasure quirk would've been so useful. But, you gotta work with what life gives you, right?
Not only did that attack fundamentally change Aizawa as a person, but it was meant to kill him in Oboro's stead. And now Mic knows this. He knows that his best friend died in a deliberate attack to kill his other best friend. And with Midnight biting it not long after this, Mic has lost the last person chillingly aware of what happened to Shirakumo. The last person he would ever be able to tell outside of Aizawa himself. Mic has to sit there and mourn his coworker in Aizawa's hospital room, fully aware that Aizawa saw the lifeless body if their best friend because the intentional, avoidable attack killed the wrong person.
There's no way that Mic isn't aware of how Aizawa's behavior changed between becoming a student and becoming a teacher. He knows him too intimately to not see the difference, the callousness that grew from such a brutal life lesson, the hope that died in his eyes when faced with reality. But he can't say a word, not to him. He can't tell Aizawa that Oboro's death and Kurogiri's creation only came about because the target was on Aizawa's head. But he's forced to know that, carrying that forbidden knowledge to his grave in the hope Shouta never finds out.
