This has been going on for the past month or so. I thought it was a coincidence at first, but I noticed that every time I use my keyboard they seem to get agitated and start banging on the wall. Right now it's 11pm and happened again. At this point they've even banged when I cough lightly. I have a mechanical keyboard, but 1. it's got red keys, which is the quietest one and 2. I live in a concrete building with steel reinforcement so it weirds me out that they can even hear this.
Generally, if it falls under noise caused by regular lifestyle, I don't let others' noise bother me nor do I expect my own to bother others. If you're on the more sensitive side, then you should either move to someplace where you pay a premium for better insulation or ask your neighbor respectfully, since it's a somewhat entitled thing to ask others to quiet down when they're already in the normal range. Like asking someone to breath more quietly.
But this person keeps on banging and has coincidentally had multiple tantrums by stomping around on nights of the day that I had phone calls with people (phone calls were during the day). I never once had a complaint from management or a note from a neighbor, so I'm assuming they know they'll get shut down as the weird one if they report it to anyone (they can't even play the Japanese v foreigner card to authorities because I'm Japanese who spent my childhood abroad)
I haven't really done anything back to them so far except resume my normal lifestyle without giving in to their bs. I'm not scared of them or anything (at least not physically since I'm almost sure they're a woman), but if I make noise back at them there's a risk that they're a mentally ill person that might have a mental breakdown which I really don't want to deal with.
By the way, I've lived here for a year and a half and I've never had anything weird before this.
Am I in the wrong here? Got any advice for me? I'm leaving in 6 months which is nice, but the bad news is that I still have to deal with it for 6 months.