会被老婆记小本本的！主要是久保的Q&A坐实了尸魂界有妾室制度……白绯更好磕了啊就要正妻！就要唯一的正妻！

Q860:尸魂界的婚姻制度和现代日本一样吗？还是像古代一样有多妻（侧室／妾）或三亲等以内的婚姻（叔侄、异母兄妹）？

A860:作为制度来说，是存在的。（古代模式）

Source: https://nanjizhidian089.lofter.com/post/30fb543d_34cc1a223

KUBO OUTSIDE Q&A

Q860: Is the marriage system in Soul Society the same as in modern Japan? Or is it like in ancient times, with polygamy (concubines) or marriages within three degrees of kinship (uncle and nephew)?

A: As a system, it exists (ancient mode).

Source: https://twitter.com/Antatica11/status/1997396599291736248