Softbank invested $1B in Coupang? Why not Japan or SEA?

I read a report from e27 that Softbank has invested $1B in Korean ecommerce company Coupang. News is referred from a Korean news site. No confirmation from Softbank so far.

I can’t understand what the Korean media is writing but if news is true, it is gonna be quite huge. Wonder why such deals don’t happen in Japan or Southeast Asia…!

Korea doesn’t have that big of a population (about 50M) but can still get such funding and traction. Japan has (100M) but doesn’t get that. Southeast Asia has 600M people in total and we don’t see equivalent traction either… It’s all quite puzzling.

Coupang must have done things very correctly and i wonder what the secret sauce is.