No one seems to mind that it's really sexual harassment... There is a reason why companies have policies against relationships between superiors and subordinates. Miyata clearly abused her power, to illustrate why that can be very wrong. Even if she wasn't, that wouldn't have been the place for starting anything. (If that isn't enough, just imagine if Kei had a girlfriend and would need to keep this job for both of them. Or Miyata being a guy. Would at some point Miyata have accepted refutal, and not only that, but without retaliation, not pursuing Nagao further, etc.? Even if Miyata did accept a rejection, her approach in the first place would have been inappropriate.)
This is just a story but it's better to be aware that something similar isn't the least bit nice in reality most of the time. (Miyata is just a role model as far as her achievements at work go. What she does to Nagao is very wrong.)