Rapephyllia: "Look, she came, so it was making love."
The significance of adoption here is that since Japan does not have same-sex marriage, the traditional way to legally connect with your partner is making your parents adopt them into your family.
This is true, it's pretty backwards but at least it can be done. This also allows your partner into the family tree, something that foreign spouses don't even get. Source: I am a foreign spouse