Even if a deceased writes a will that excludes a spouse or child, under Japanese law, a spouse can almost always claim a portion of the estate by right. This portion may not be as large as the spouse would have received if there had been no will at all, but this provision is meant to ensure that spouses will always receive something upon the death of their partner.
Spouses who are worried that their partner might file a fraudulent divorce registration in Japan can file a Non-Acceptance of Notification of Divorce (rikon fujuri moshidesho 離婚不受理申出書) in order to prevent acceptance of a divorce form. While this non-acceptance used to only last for 6 months, in 2008 the law was changed to allow such non-acceptance to be valid until withdrawn by the submitting spouse.
There are two types of spousal visas in Japan, one for spouses of Japanese citizens and one for spouses of permanent residents of Japan, although both visas are substantially the same. Therefore, it is possible for a foreign national to receive a visa to enter Japan even if his/her spouse is only a Japanese permanent resident.
To obtain a court-ordered divorce in Japan, there must be statutorily recognized reason for granting the divorce. Adultery is one of those five recognized reasons. However, while adultery does provide a potential basis for divorce, divorce will not be automatically granted when one spouse has been unfaithful.