Divorce
Separation of assets
About the risk of mixing pre-marriage assets
2021-08 thread on marital assets
In addition, some assets gained during marriage would not be considered marital asset but are at risk to be mixed together : gift made to a specific spouse, or inheritances received by one of the spouse for example.
Alimony and child support
Japan courts have issued standard tables to calculate 'alimony' and 'child support' amounts, revised in December 2019.
Official link for the different tables (in japanese) : https://www.courts.go.jp/toukei_siryou/siryo/H30shihou_houkoku/index.html
Explanation for this system in english, including how to read the tables : https://alesia-law.com/en/2020/04/new-calculation-table-for-child-support-and-alimony/