Hi Boats & Hos
With regards to the contract being a long time, 4 years there are clauses to address this issue... If you need to change from commuting to non-commuting or vise/versa you may do it once with no reason needed... If you have mitigating circumstances you may be allowed to change again during the term...
If you are tired of Japan, have life changes or just want to leave there is a resignation clause... The time required depends on the Crew Lease Company you are with which ranges from 35-90 days notice...
Also if there are changes in the T&C due to market forces they have amended current contracts to reflect the enhancements in the past...
Kampai, Jpncrjdriver