天命を革める　[てんめいをあらためる]　tenmei o aratameru, lit. "restoring God's Will"; also known as ekisei kakumei (易姓革命), meaning a change of dynasty (lit. "predicted name change") decreed by Heaven when the incumbent emperor is found to be lacking in moral virtue.

舒　[じょ]　Jo, surname of the late empress Yo-o
張　[しょう]　Chou, surname of the late king of Kou

張精　[ちょうせい]　Chou Sei, Rakushun's formal name; "Rakushun" is his azana; Rakushun and the late king of Kou share the same surname, though this no more implies a relationship than two people both named Johnson or Smith. In all of China, the 100 most common surnames, in a population of 1.3 billion, account for over 85 percent of the population. It's even worse in South Korea, with 22 surnames making up 80 percent of the population. In the U.S., thanks to immigration, the top 300 surnames come to only 35 percent. Apparently, the Divine Decrees still apply, though.

"A marriage may be registered under either spouse's census records." When a marriage is registered under the wife's koseki (census record), it is known as a muko-iri (婿入), or son-in-law marriage. In the anime series Kodocha, because Sana is an only child and a girl, even though she is still in sixth grade, her mother firmly informs her that when she marries, it will be a muko-iri marriage and her husband must adopt her surname.

In other words, don't start dating a boy who doesn't know the ground rules going in.

And when her classmate Tsuyoshi's parents get divorced (meaning that his mother's name would be removed from his father's koseki) and Tsuyoshi's mother gets custody, his teacher actually announces in class that henceforth he will use his mother's maiden name. Is essense, according to the family registration laws, his mother's family has taken custody of him.

The divorce rate in Japan: 2.27/1000 population; in the U.S: 4.1/1000 population.

"However, you can bestow the rank of royal consort upon a companion, such as queen or prince." Prince can refer to both a son and husband. The husband of Queen Victoria was Prince Albert; the husband of Queen Elizabeth is Prince Philip.