The main ports (based on throughput) are:

1 Nagoya Port? Nagoya Port

2 Chiba Port? Chiba

3 Yokohama Port? Yokohama?

Fourth place or less: Tomakomai Port? Tomakomai?, Mizushima Port? Mizushima, Kawasaki Port? Kawasaki, Osaka Port? Osaka, Kitakyushu Port? Kitakyushu, Tokyo Port? Tokyo, Kobe Port ?Kobe

Reference pictures of other designated ports:?)