Koseki

Koseki is a big book that people in Japan use to keep track of important information about their family. This book has lots of pages, and on each page, there is space for one family, with all the important information about that family written down.

The koseki book has a lot of important information about each family. For instance, it has the names of all the family members, including the parents, children, and sometimes even grandparents. It also has information about where each family member was born, what their gender is, and when they were born.

If someone gets married in Japan, their information gets added to their spouse's koseki book. The koseki book is also used when someone dies, because their information gets taken out of the book.

The koseki book is really important in Japan because it helps people keep track of their family history. It can also be used for things like getting a passport, registering to vote, or getting married. That's why it's really important to make sure all the information in the koseki book is accurate and up-to-date.