@Whatafool123
I haven't been to Japan for many years, but my experience then suggested that the Japanese are also far better at following rules than we are, and I would imagine were wearing masks from the very start of this. Their diet is, of course, healthier than ours with lower rates of obesity, as you say, but I should imagine that all these factors have contributed to their low mortality rate.
The situation in Japan is very different from The UK. There is no strict lockdown. Businesses are open, but some have reduced hours. People can travel freely, visit family. Go to the supermarket or restaurants as a family. Working from home is encouraged, but not essential. Schools are open. Yes, most people do wear masks. Kids aged 3 and over are expected to wear masks at school/nursery. Kids eat lunch in the classroom, so teachers watch them and make sure they don't talk while eating and their masks off. I haven't seen anyone in the supermarket without a mask, except babies.
So, Japan doesn't have a strict lockdown, but has lower rates of obesity and people are generally healthier and more active than the UK. Furthermore, everyone who tests positive is hospitalised either in a hospital or a special hotel. Everyone! Even if they have no symptoms. I can't help but think that this is a major factor in the low death rate in Japan too as people with covid are being monitored very closely.
However, if you compare countries like the US and Canada. They have many similarities, but a very different death rate, so I think this is mostly due to Canada's stricter measures.
It is almost definitely a combination of factors. The Japanese people would never stand for a strict lockdown like the UK, but British people would never stand for universal mask wearing and compulsory hospitalisation like Japan. I feel people are right when they said the UK hit a perfect storm. High obesity, lots of health problems, slow government response, low rates of medical treatment. The UK does have a strict lockdown, but I suspect low rates of compliance. Even my parents, who are quite sensible and careful have visited friends for a coffee and had the neighbor over for lunch.