So sad how the kindest people often struggle the most inside. As a woman in a chauvinistic environment, I'm sure she had to be perfect just to survive, show no signs of weakness to anyone. So she tried to cope by making someone else's life less miserable. But everyone needs a shoulder to lean on sometimes. She must have suffocated long before she hung herself.
The kindest are the most broken... the fact that she was still able to be strong for her underclassman while being harassed.. Arata is not wrong that she is strong, she's still strong. It's just that even the strongest needs a break but Michiru probably never got it, that she reached her limit. But the fact won't ever change how strong she was for enduring all of that... T_T