My child is 11 now but will be 12 when we go to Japan. Is he/she eligible for the JR child pass?

Yes, children who are 11 years of age when the Exchange Order is issued are eligible for the discounted child Japan Rail Pass.

The general rules of JR Group state that children from the ages of 6 to 11 are eligible for the discounted Japan Rail Pass. Those who are younger than 6 do not require a Japan Rail Pass as they can travel for free. However, seat reservations are not available for children under 6.