Company went back to office, can the fire me?

tldr;

Company went BTO, with exception for people who live too far away for daily commute at the time of rule change, like me. 正社員, white guy with PR. Can they fire me, if they tighten the rule further?

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I (M35) joined my Tokyo based company during Corona, full remote living not in Kanto. About 10% of other people also did not live in Kanto. During the interviews they strongly promoted the fact they are full remote and seemed to see benefits of having country wide talent pool.

This is basically the perfect job for me and I felt I won't have to move back to Tokyo. So I bought a house here.

Fast forward a couple of years, my company started to request coming to office once a week. Than twice a week. Than made it mandatory for people in Kanto. Now we are at at least 10 days per month, excepting people with small children and people who lived remote before the bto call. The idea is to improve communication and inter-team visibility, so we can better understand the shared vision. During the explanation, they said anyone not on board with it is not needed anymore.

I make an effort to go to office twice a month, I can do day trips without problem, but since I have to take the Shinkansen it is fairly expensive for my company.

Now there is a post on slack from upper management, explaining what we "lost" while working full remote. Anxiety to get fired at some point in near future grew again. Realistically what can they do? What kind of protection do I have, e.g. could I expect severance pay?

I have decided to stay until I don't have a choice any more, but I want to know what i can expect.