Forget Japan, even JL pilots are losing jobs and going to KE in dozens.
If you're considering KE, have a serious thought. The union is taking the company to court due to interpretation of contract clause and it is not impossible to see big change this year. No pay raise in foreseeable future as too many pilots still applying, the locals are not welcoming, with 500 PIC, and no exposure of how to deal with the locals here, I think it's suicidal for your OE even if you're lucky to get pass recruitment SIM check.
I was in KE for long time, and am now in China, just to make the most out of my not too many remaining years of flying, they pay well compared to KAL, but you have to bear with many other different issues, like unhealthy local food, terrible manners (both Korea and China very similar in their lack of manners), very costly good western food and polluted air.
After you clock enough hours, and make enough trips to China and Korea to judge by yourself whether it's suitable for you and your family, then perhaps decide from there.