By default, the following groups are created automatically. You cannot delete these groups.
You also cannot create a group with the same name mentioned below.

A group indicating all users of cybozu.cn.

A group indicating cybozu.cn Administrators.
cybozu.cn Administrators

This group can be used only by the system.

It is a group shown as "Login user" on the screen.
It can be used to configure access permissions, filters, and notifications.

Users can use "Login user" when they want to filter the data made by themselves.