Relocating dog from Korea to Japan

Hello.
I have to move from Korea(Busan) to Japan(Tokyo) in March next year with my 13kg 5 y.o. mixed dog.
I took him from an animal shelter 3 years ago, and he is quite an anxious/fearful dog. I've tried different things, but even now he is still scared of rain sounds, loud noises, people, etc.
Recently, I've finally found a dog school for him, and he goes there twice a week.

The question is: what is the best way to relocate him?

There are 2 options as I know of.
The 1st is going by ferry: (12hours from Busan to Fukuoka, arrive in the morning and in the evening board the next ferry (~24 hours) from Fukuoka to Tokyo.
And 2nd is going by plane in cargo(~4 hours if you count from the time of check-in). (thinking of flying with JAL)

Thank you!