Alright, I'm honestly getting sick of the "it's against the law/unsupported by the law" excuses that keep getting thrown around.

Articles 731-737 of the Japanese Civil Code restrict marriage to opposite-sex unions. Same-sex couples are not able to marry, and same-sex couples are not granted rights derived from marriage. Also same-sex marriages performed abroad are not legally recognized in Japan and bi-national same-sex couples cannot obtain a visa for the foreign partner based on their relationship.[10]

In March 2009 Japan Today reported that the Justice Ministry plans to allow Japanese nationals to marry same-sex partners in countries where same-sex marriage is legal. The ministry will issue certificates necessary for such marriage of Japanese citizens and foreigners, the sources said, adding the ministry will soon convey the decision to its legal affairs bureaus across the nation, the sources said. Though the marriage will not necessarily be legally recognised within Japan, allowing its citizens to marry same-sex partners overseas is seen by some as a first step toward eventual legalization of gay marriage in Japan.[11] Also, should this law pass, Japan would be the first Asian country in modern history to legally allow same-sex marriage within its borders.

In the meantime, Japan does have a form of domestic partnership (DP) for same-sex couples. The DP, known as KOUSEISHOUSHO (公正書証) gives many if not most of the rights of married couples, including inheritance and rights to assets of the other partner, the right to full knowledge of the medical condition of the other partner, including medical consultations, nursing care, hospital visits, and rights to healthcare proxy (in the case where one partner is unable to make decisions for his/herself), among other things. (from the book on same-sex parternship in Japan 「同性パートナー生活読本」(http://webcatplus.nii.ac.jp/webcatpl...k/6980828.html) by Nagayasu Shibun 3/2/3003 Published by Ryokufuku Publishing, Tokyo (http://www.ryokufu.com/top.html)
FYI: Unrecognized =/= against the law. Simply put they just don't view your certificate of marriage as legal. Meaning there is no rules against it showing up in the game.