Yeah I'm curious myself. It seems like no specific policy can clearly explain the results. IIRC Japan is one of the later countries to restrict travel from Chin

Yeah I'm curious myself. It seems like no specific policy can clearly explain the results. IIRC Japan is one of the later countries to restrict travel from China back when cases were high there and in general did limited testing on their population. Maybe the public hygiene practice and culture of wearing masks really helped, or maybe the infection is still developing there.