I was tired of traveling by highway bus, train, and airplane, so I took the ferry.
It takes about 32 hours to travel from Tokyo Port to Kitakyushu (Shin Moji Port). The reason it takes so long is because it passes through Shikoku Tokushima Port on the way.
The Ocean Tokyu Ferry I used for the trip is not a passenger ferry but a cargo ferry, so there are only vending machines for meals and no Wi-Fi on board.
Ocean Tokyu Ferry ( https://www.otf.jp/ )
On the other hand, Tokyo Kyushu Ferry’s ferry from Yokosuka to Shin Moji takes about 21 hours, has a restaurant/cafe, and offers onboard Wi-Fi.
Tokyo Kyushu Ferry ( https://tqf.co.jp/ )
For more information, please check the above website.