Second Cousins, Cousins Once Removed and Third Cousins in Japanese: Hatoko, Itoko-chigai and Mi-itoko, with Degrees of Kinship

First, a refresher on cousins (itoko): your parent's sibling's child, 4th degree

A cousin (itoko) is the child of your parent's sibling (your uncle or aunt). Your common ancestors are your grandparents: you go up 2 generations to them and down 2 through the uncle or aunt to the cousin, making a cousin a collateral blood relative of the 4th degree. (Japan counts degrees the civil-law way: generations up to the common ancestor plus generations down.)

In kanji, a male cousin is written 従兄弟 and a female cousin 従姉妹, and they can be distinguished by age relative to you as 従兄 (juukei, older male), 従弟 (juutei, younger male), 従姉 (juushi, older female) and 従妹 (juumai, younger female). All of them can simply be read "itoko". People sometimes also distinguish cousins on the father's side ("chichikata no itoko") from those on the mother's side ("hahakata no itoko").

Every relative that follows can be sorted out using the cousin as the reference point: either the generation is shifted by 1 (itoko-chigai), or the common ancestor is 1 generation further up (hatoko).

What itoko-chigai is: a cousin shifted by one generation, 5th degree

Itoko-chigai, a cousin once removed, is a relative on the same branch as a cousin but 1 generation off. There are 2 kinds, shifted down (your cousin's child) or up (your parent's cousin), and both are called itoko-chigai.

For a cousin's child, you go up 2 generations to your common ancestors, your grandparents, and down 3 through your cousin, so 2 + 3 = 5th degree. For a parent's cousin, you go up 3 generations to your common ancestors, your great-grandparents, and down 2, so 3 + 2 = 5th degree. The direction is reversed, but the degree is the same.

What hatoko is: children of cousins, 6th degree

Hatoko are the grandchildren of your grandparent's siblings. In other words, they're the children of people who are cousins to your parents, and your common ancestors are your great-grandparents. You go up 3 generations to the great-grandparents and down 3, so a second cousin is a collateral blood relative of the 3 + 3 = 6th degree.

• Kanji: 再従兄弟 (male) and 再従姉妹 (female). 再 means "one step further".
• Other names: mata-itoko, futa-itoko. The term varies by region, but the relationship is the same.
• Example trace: father → his father (grandfather) → his older brother (great-uncle) → his son (parent's cousin) → his son (second cousin).
• At 6th degree, second cousins just make it into the relatives defined by the Civil Code (blood relatives within the 6th degree).

Since second cousins are the same generation, they often meet as playmates of a similar age at memorial services or family visits. But parents sometimes introduce them as "cousins", and some people grow up never quite knowing whether someone is a cousin or a second cousin. Asking your parent "Is that person's grandfather our grandfather's brother?" will tell you whether they're a second cousin.

Third cousins and second cousins' children: from the 7th degree they're no longer Civil Code relatives

One step beyond hatoko are mi-itoko (三従兄弟, 三従姉妹), third cousins. They're the great-grandchildren of your great-grandparent's siblings: your parents are second cousins and your grandparents are cousins. Your common ancestors jump all the way back to your great-great-grandparents (your great-grandparents' parents).

Trace "father → father → father → older brother → son → son → son" (the great-grandchild of your great-grandfather's older brother) in the Kinship Degree & Relationship Calculator and it shows the 8th degree. You go up 4 generations to your common ancestors, the great-great-grandparents, and down 4, so 4 + 4 = 8th degree. Going just one step further than second cousins adds 2 degrees. The Civil Code's relatives stop at the 6th degree, so third cousins aren't legal relatives even though they're related by blood.

Japan's restriction on marriage (Civil Code Article 734) covers collateral blood relatives only up to the 3rd degree, so cousins, cousins once removed, second cousins and third cousins can all legally marry. The scope of relatives and the rules on marriage and inheritance are summarized in How to Count Degrees of Kinship, with a Quick Reference Table.

How to check whether someone is a cousin or second cousin

The more distant the relative, the fewer people know where the branches split. To confirm a relationship, check in the following order.

1. 1

   Ask who the common ancestor is

   Ask your parents or grandparents, "Where do we and that person branch off?" If the common ancestors are your grandparents, they're on the cousin line; if your great-grandparents, the second-cousin line.

2. 2

   Count which generation they're in

   Count how many generations down from the common ancestor the person is. If they're in your generation, they're a cousin or second cousin; if 1 generation off, a cousin once removed, and so on.

3. 3

   If necessary, go back through the family register

   When you need the exact relationship, for example for inheritance, obtain family register (koseki) transcripts going back through your parents, grandparents and great-grandparents. With nationwide koseki issuance, you can request your direct-line registers together at your nearest municipal office even if they're registered far away.

The same degree can mean very different relationships. A second cousin, a cousin's grandchild and a grandparent's cousin are all 6th degree, but the second cousin is your generation, the cousin's grandchild 2 generations down and the grandparent's cousin 2 generations up. Degree only measures closeness, so when choosing a term you also need to look at the generation shift.

From your child's point of view, every term shifts by one

Kinship terms change depending on whose point of view you take. Once you have a child, your cousin relationships look like this from the child's point of view.

• Your cousin → your child's "parent's cousin" (cousin once removed, 5th degree)
• Your cousin's child → your child's "second cousin" (6th degree)
• Your second cousin → your child's "parent's second cousin" (7th degree)
• Your sibling's child (nephew or niece) → your child's "cousin" (4th degree)

In other words, when cousins get together with their children, the children are second cousins to each other. You can say "these kids are second cousins" at a family gathering or in a New Year card photo when their parents are cousins.

If a relationship gets too long to follow, tap "father", "mother", "older brother", "son" and so on in order from yourself in the Kinship Degree & Relationship Calculator. It shows the term and reading, alternative terms (such as itoko-chigai) and the degree, with a family tree.

FAQ

Are hatoko and mata-itoko different?

They're the same relationship. Hatoko, mata-itoko and futa-itoko all refer to the grandchildren of your grandparent's siblings (children of cousins), written 再従兄弟 or 再従姉妹 in kanji. They're collateral blood relatives of the 6th degree.

What do you call your cousin's child in Japanese?

"Itoko-chigai". In kanji, a boy can also be written 従甥 (juusei) and a girl 従姪 (juutetsu). They're collateral blood relatives of the 5th degree and count as relatives under the Civil Code. From your own child's point of view, your cousin's child is a "hatoko" (second cousin).

What do you call your parent's cousin in Japanese?

This is also "itoko-chigai". It can be written 従伯叔父 (itoko-oji) or 従伯叔母 (itoko-oba), and it's a collateral blood relative of the 5th degree. In conversation, people usually say something like "my father's cousin, Uncle XX".

Do second cousins count as relatives?

Yes. Relatives under the Civil Code include blood relatives within the 6th degree, so second cousins at the 6th degree just make it. A second cousin's child (7th degree) and third cousins (8th degree) are related by blood but aren't relatives under the Civil Code.

Can you marry a second cousin in Japan?

Yes. Civil Code Article 734 prohibits marriage between direct blood relatives and collateral blood relatives within the 3rd degree (siblings, uncles and aunts, nephews and nieces). There are no legal restrictions on marrying a cousin (4th degree) or second cousin (6th degree).