This is a massive wish fulfilment fantasy for simps, isn't it? To live in a world where woman throw themselves at you, and you don't even need to make an effort or even be nice to them...
As for the harem tag and the yanderes and psychos, I don't need the drama and will drop this now. If the writer cannot even come up with a single original idea (no, changing the ratio is not an original idea)
Based on what is known in this 1:5 male to female ratio world, if you genderbend the MC + his harem (the isekai world basically), and flip the gender ratio + social & gender dynamics of this isekai world, then you get an otome game. Instead of 5 cute (mc's opinion) girls chasing the same above average (harem's opinion) guy, it's 5 cool (fmc' opinion) guys chasing a the same above average (harem's opinion) girl.
Btw, this only works if MC's original world = our world = f(x)
1:5 male to female isekai world = f'(x)
genderbent 1:5 male to female isekai world = f''(x)