Food poisoning can happen in any restaurant, not just a McDonald's issue.
If the response is handled properly, it will be fine.
And by being aware of such incidents, I think there is no problem at all.
I think it will decline for a while, so I will consider entering after confirming the lowest price.

I'll wait a little longer even if I hear it's expensive.
I'm considering entering at 1400 yen.
Overall, the stock market is down, so I don't think it's due to just Tokyo Metro.
It seems that the overall stock prices will start moving based on the election results next week.