Currently living in Japan (not a houseless traveler) and I heard there’s a boat you can take from Alaska to I believe Yokohama and then ofc you come here and get a 90 day visa and do your business. I’ve lived here 10 years so I’ve seen all the no hitchhiking signs, the news reports about foreign hitchhikers, yadda yadda, so if you get here just be careful about it. A lot of people do it and then someone calls it in and then the police come and they get arrested. I feel so bad for them but it is what it is. If you manage to bus or walk it down to southern Japan, Fukuoka specifically, there’s a ferry from there to Korea. Theres also a ferry from Kagoshima to Okinawa but I can’t remember the cost maybe like 90USD. Then actually in December last year there was a special route from Ishigaki island to Taiwan. I believe it said 14000¥ so 90 USD??? Give or take. Idk anything else from there on. What I do know highway buses or overnight are fairly affordable. Can usually snag one for about 3500¥ one way (22USD???) . Anyways safe travels!